Fix NXP MCUXpresso CIFAR link failure (pytorch#24510)

Main-branch counterpart of release/1.6 fix pytorch#24509. Fixes the NXP
MCUXpresso failure seen on pytorch#24490; main has the same incomplete CMake
target.

The [failed
job](https://github.com/pytorch/executorch/actions/runs/41601038988/job/125799646998)
reaches the final CIFAR firmware link, then fails with `undefined
reference to SYS_INFO_PrintAll`. The SDK example calls this helper, but
our standalone CMake target omits
`examples/eiq_examples/common/sys_info/sys_info.c`.

Add that source to the firmware target. The helper also needs
`MCUXSDK_VERSION_FULL_STR`, which the SDK's normal build supplies
through a generated header. Our standalone target now uses the SDK's
`mcux_version.cmake` parser and sets the equivalent compile definition
from the checked-out SDK version.

## Verification

A focused host CMake build reused the actual example target's source
list and include paths, the real SDK helper/header, and the SDK version
parser. The board/runtime sources were replaced with empty fixtures and
the application with a small C++ caller.

The original source list reproduced the unresolved `SYS_INFO_PrintAll`
link error. Adding only the helper reproduced the missing
`MCUXSDK_VERSION_FULL_STR` compile error. With both changes, the
executable linked and printed `MCUX SDK version: 2026.12.00-pvw1`.

`git diff --check` passed. The full ARM firmware build and execution on
hardware were not run locally; the NXP CI job must validate the complete
build.

Only the example's CMakeLists.txt changes (eight added lines). The
resulting file is byte-identical to the verified release fix in pytorch#24509.
Land this on main; pytorch#24509 is the corresponding release/1.6 pick.

Prepared with OpenAI Codex.

Author: JacobSzwejbka

examples/nxp/mcuxpresso/imxrt700/executorch_cifarnet/CMakeLists.txt

@@ -58,6 +58,7 @@ add_executable(
   ${SdkRootDirPath}/examples/eiq_examples/executorch_cifarnet/main.cpp
   ${SdkRootDirPath}/examples/eiq_examples/executorch_cifarnet/RegisterKernels.cpp
   ${SdkRootDirPath}/examples/eiq_examples/common/timer.c
+  ${SdkRootDirPath}/examples/eiq_examples/common/sys_info/sys_info.c
   ${SdkRootDirPath}/devices/RT/RT700/MIMXRT798S/startup_MIMXRT798S_cm33_core0.c
   ${EXECUTORCH_ROOT_DIR}/backends/nxp/runtime/NeutronBackend.cpp
   ${SdkRootDirPath}/middleware/tfm/tf-m/platform/ext/common/syscalls_stub.c
@@ -83,6 +84,13 @@ add_executable(
   ${SdkRootDirPath}/components/debug_console_lite/fsl_debug_console.c
 )
 
+# sys_info.c needs the version macro supplied by the SDK's normal build system.
+include(${SdkRootDirPath}/cmake/extension/mcux_version.cmake)
+target_compile_definitions(
+  ${MCUX_SDK_PROJECT_NAME}
+  PRIVATE "MCUXSDK_VERSION_FULL_STR=\"${MCUXSDK_VERSION_FULL}\""
+)
+
 target_include_directories(
   ${MCUX_SDK_PROJECT_NAME}
   PRIVATE