[WPE][GTK] Build error in in ARM64 after 254645@main

[Diego Pino]

While building WebKitGTK/WPE in ARM64 using LibWebRTC, I get the following build error:

```
FAILED: Source/ThirdParty/libwebrtc/CMakeFiles/webrtc.dir/Source/webrtc/common_audio/fir_filter_sse.cc.o
<CXX>  -DBUILDING_WEBKIT=1 -DBUILDING_WITH_CMAKE=1 -DBUILDING_WPE__=1 -DDYNAMIC_ANNOTATIONS_ENABLED=1 -DEXPAT_RELATIVE_PATH -DGETTEXT_PACKAGE=\"WPE\" -DHAVE_CONFIG_H -DHAVE_CONFIG_H=1 -DHAVE_LRINT -DHAVE_LRINTF -DHAVE_NETINET_IN_H -DHAVE_SCTP -DHAVE_STDINT_H -DHAVE_STDLIB_H -DHAVE_UINT64_T -DHAVE_WEBRTC_VIDEO -DHAVE_WEBRTC_VOICE
In file included from ../../../Source/ThirdParty/libwebrtc/Source/webrtc/common_audio/fir_filter_sse.cc:15:
In file included from /usr/lib/llvm-12/lib/clang/12.0.0/include/xmmintrin.h:13:
/usr/lib/llvm-12/lib/clang/12.0.0/include/mmintrin.h:33:5: error: use of undeclared identifier '__builtin_ia32_emms'; did you mean '__builtin_isless'?
    __builtin_ia32_emms();
    ^
/usr/lib/llvm-12/lib/clang/12.0.0/include/mmintrin.h:33:5: note: '__builtin_isless' declared here
/usr/lib/llvm-12/lib/clang/12.0.0/include/mmintrin.h:33:25: error: too few arguments to function call, expected 2, have 0
    __builtin_ia32_emms();
    ~~~~~~~~~~~~~~~~~~~~^
/usr/lib/llvm-12/lib/clang/12.0.0/include/mmintrin.h:50:19: error: use of undeclared identifier '__builtin_ia32_vec_init_v2si'
    return (__m64)__builtin_ia32_vec_init_v2si(__i, 0);
```

It seems the build is using x86 SSE instead of ARM64 NEON.

[Diego Pino]

Pull request: https://github.com/webkit/webkit/pull/4663

[EWS]

Committed 254931@main (e89fe2bc8167): <https://commits.webkit.org/254931@main>

Reviewed commits have been landed. Closing PR #4663 and removing active labels.

[Radar WebKit Bug Importer]

<rdar://problem/100480564>