Doesn't compile without `avcodec`

[TheWastl]

Looks like it wants to perform some sort of version check.

> RUST_BACKTRACE=1 cargo build --no-default-features
   Compiling ffmpeg-sys v4.3.3 (/home/wastl/rust-ffmpeg-sys)
error: failed to run custom build command for `ffmpeg-sys v4.3.3 (/home/wastl/rust-ffmpeg-sys)`

Caused by:
  process didn't exit successfully: `/home/wastl/rust-ffmpeg-sys/target/debug/build/ffmpeg-sys-9303192e62d3579d/build-script-build` (exit status: 101)
  --- stdout
  cargo:rerun-if-env-changed=LIBAVUTIL_NO_PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_SYSROOT_DIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR
  cargo:rerun-if-env-changed=SYSROOT
  cargo:rerun-if-env-changed=PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_SYSROOT_DIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR
  cargo:rustc-link-search=native=/usr/lib/x86_64-linux-gnu
  cargo:rustc-link-lib=avutil
  cargo:rerun-if-env-changed=LIBAVCODEC_NO_PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_SYSROOT_DIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR
  cargo:rerun-if-env-changed=SYSROOT
  cargo:rerun-if-env-changed=PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64-unknown-linux-gnu
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64_unknown_linux_gnu
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_SYSROOT_DIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR
  cargo:rustc-link-search=native=/usr/lib/x86_64-linux-gnu
  cargo:rustc-link-lib=avcodec
  OPT_LEVEL = Some("0")
  HOST = Some("x86_64-unknown-linux-gnu")
  CC_x86_64-unknown-linux-gnu = None
  CC_x86_64_unknown_linux_gnu = None
  HOST_CC = None
  CC = None
  CFLAGS_x86_64-unknown-linux-gnu = None
  CFLAGS_x86_64_unknown_linux_gnu = None
  HOST_CFLAGS = None
  CFLAGS = None
  CRATE_CC_NO_DEFAULTS = None
  DEBUG = Some("true")
  CARGO_CFG_TARGET_FEATURE = Some("fxsr,sse,sse2")

  --- stderr
  Using stack size: Ok(3145728)
  check.c: In function ‘main’:
  check.c:198:63: error: ‘LIBAVCODEC_VERSION_MAJOR’ undeclared (first use in this function); did you mean ‘LIBAVUTIL_VERSION_MAJOR’?
    198 |             printf("[avcodec_version_greater_than_56_0]%d\n", LIBAVCODEC_VERSION_MAJOR > 56 || (LIBAVCODEC_VERSION_MAJOR == 56 && LIBAVCODEC_VERSION_MINOR > 0));
        |                                                               ^~~~~~~~~~~~~~~~~~~~~~~~
        |                                                               LIBAVUTIL_VERSION_MAJOR
  check.c:198:63: note: each undeclared identifier is reported only once for each function it appears in
  check.c:198:131: error: ‘LIBAVCODEC_VERSION_MINOR’ undeclared (first use in this function); did you mean ‘LIBAVUTIL_VERSION_MINOR’?
    198 |             printf("[avcodec_version_greater_than_56_0]%d\n", LIBAVCODEC_VERSION_MAJOR > 56 || (LIBAVCODEC_VERSION_MAJOR == 56 && LIBAVCODEC_VERSION_MINOR > 0));
        |                                                                                                                                   ^~~~~~~~~~~~~~~~~~~~~~~~
        |                                                                                                                                   LIBAVUTIL_VERSION_MINOR
  thread 'ffmpg-sys-build' panicked at 'Compile failed', build.rs:488:9
  stack backtrace:
     0: std::panicking::begin_panic
               at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633/library/std/src/panicking.rs:541:12
     1: build_script_build::check_features
               at ./build.rs:488:9
     2: build_script_build::thread_main
               at ./build.rs:765:5
     3: core::ops::function::FnOnce::call_once
               at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633/library/core/src/ops/function.rs:227:5
  note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
  thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Any { .. }', build.rs:629:10
  stack backtrace:
     0: rust_begin_unwind
               at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633/library/std/src/panicking.rs:515:5
     1: core::panicking::panic_fmt
               at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633/library/core/src/panicking.rs:92:14
     2: core::result::unwrap_failed
               at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633/library/core/src/result.rs:1355:5
     3: core::result::Result<T,E>::unwrap
               at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633/library/core/src/result.rs:1037:23
     4: build_script_build::main
               at ./build.rs:623:5
     5: core::ops::function::FnOnce::call_once
               at /rustc/a178d0322ce20e33eac124758e837cbd80a6f633/library/core/src/ops/function.rs:227:5
  note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

The other components can be turned off without problems (i.e. cargo build --no-default-features --features avcodec runs fine).