i686 build, wasm3 won't build

[X7md]

I'm trying to cross compile txiki.js targeting i686 Linux, but

libtool: warning: remember to run 'libtool --finish /usr/local/lib'
In file included from /usr/include/features.h:486,
                 from /usr/include/bits/libc-header-start.h:33,
                 from /usr/include/stdio.h:27,
                 from /content/txiki.js/deps/wasm3/source/m3_core.h:11,
                 from /content/txiki.js/deps/wasm3/source/m3_api_wasi.h:11,
                 from /content/txiki.js/deps/wasm3/source/m3_api_wasi.c:10:
/content/txiki.js/deps/wasm3/source/extra/wasi_core.h:46:1: error: negative width in bit-field ‘__error_if_negative’
   46 | _Static_assert(_Alignof(int64_t) == 8, "non-wasi data layout");
      | ^~~~~~~~~~~~~~
compilation terminated due to -Wfatal-errors.
gmake[2]: *** [deps/wasm3/source/CMakeFiles/m3.dir/build.make:93: deps/wasm3/source/CMakeFiles/m3.dir/m3_api_wasi.c.o] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:1717: deps/wasm3/source/CMakeFiles/m3.dir/all] Error 2
gmake[1]: *** Waiting for unfinished jobs....
gmake: *** [Makefile:136: all] Error 2

My build steps:

https://gist.github.com/X7md/cac8f5a83b947452175de35491a12987

[bnoordhuis]

int64_t alignment on 32 bits architectures can be either 4 or 8 bytes so the check is wrong-ish. I'm guessing wasm3 doesn't get tested much on i686. It should be safe to remove that assert and the next one.