Build of Qt on macOS 26 (Tahoe) with the matching macOS 26 SDK and Xcode 26 version (Apple clang 17) leads to a build failure:

```
No such file or directory: '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/metallib'
```

The full build log is there: https://github.com/Homebrew/homebrew-core/pull/243852
The end of the build log is:

```
2025-09-16T13:44:53.7193360Z [6765/21731] /opt/homebrew/opt/python@3.13/Frameworks/Python.framework/Versions/3.13/bin/python3.13 ../../../../../../qtwebengine/src/3rdparty/chromium/third_party/angle/src/libANGLE/renderer/metal/shaders/metal_wrapper.py /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/metallib gen/angle/mtl_internal_shaders_autogen.air -o gen/angle/mtl_internal_shaders_autogen.metallib
2025-09-16T13:44:53.7194530Z FAILED: [code=1] gen/angle/mtl_internal_shaders_autogen.metallib
2025-09-16T13:44:53.7195710Z /opt/homebrew/opt/python@3.13/Frameworks/Python.framework/Versions/3.13/bin/python3.13 ../../../../../../qtwebengine/src/3rdparty/chromium/third_party/angle/src/libANGLE/renderer/metal/shaders/metal_wrapper.py /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/metallib gen/angle/mtl_internal_shaders_autogen.air -o gen/angle/mtl_internal_shaders_autogen.metallib
2025-09-16T13:44:53.7196810Z Traceback (most recent call last):
2025-09-16T13:44:53.7197520Z File "/private/tmp/qt-20250916-13570-td3obe/qt-everywhere-src-6.9.2/build/qtwebengine/src/core/Release/arm64/../../../../../../qtwebengine/src/3rdparty/chromium/third_party/angle/src/libANGLE/renderer/metal/shaders/metal_wrapper.py", line 15, in <module>
2025-09-16T13:44:53.7198230Z sys.exit(main(sys.argv[1:]))
2025-09-16T13:44:53.7198390Z ~~~~^^^^^^^^^^^^^^
2025-09-16T13:44:53.7199080Z File "/private/tmp/qt-20250916-13570-td3obe/qt-everywhere-src-6.9.2/build/qtwebengine/src/core/Release/arm64/../../../../../../qtwebengine/src/3rdparty/chromium/third_party/angle/src/libANGLE/renderer/metal/shaders/metal_wrapper.py", line 11, in main
2025-09-16T13:44:53.7199920Z return subprocess.run(args, stdout=subprocess.PIPE, text=True).returncode
2025-09-16T13:44:53.7200210Z ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2025-09-16T13:44:53.7200640Z File "/opt/homebrew/Cellar/python@3.13/3.13.7/Frameworks/Python.framework/Versions/3.13/lib/python3.13/subprocess.py", line 554, in run
2025-09-16T13:44:53.7201090Z with Popen(*popenargs, **kwargs) as process:
2025-09-16T13:44:53.7201290Z ~~~~~^^^^^^^^^^^^^^^^^^^^^^
2025-09-16T13:44:53.7201760Z File "/opt/homebrew/Cellar/python@3.13/3.13.7/Frameworks/Python.framework/Versions/3.13/lib/python3.13/subprocess.py", line 1039, in _init_
2025-09-16T13:44:53.7202240Z self._execute_child(args, executable, preexec_fn, close_fds,
2025-09-16T13:44:53.7202490Z ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2025-09-16T13:44:53.7202680Z pass_fds, cwd, env,
2025-09-16T13:44:53.7202860Z ^^^^^^^^^^^^^^^^^^^
2025-09-16T13:44:53.7203020Z ...<5 lines>...
2025-09-16T13:44:53.7203160Z gid, gids, uid, umask,
2025-09-16T13:44:53.7203330Z ^^^^^^^^^^^^^^^^^^^^^^
2025-09-16T13:44:53.7203520Z start_new_session, process_group)
2025-09-16T13:44:53.7203720Z ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2025-09-16T13:44:53.7204160Z File "/opt/homebrew/Cellar/python@3.13/3.13.7/Frameworks/Python.framework/Versions/3.13/lib/python3.13/subprocess.py", line 1972, in _execute_child
2025-09-16T13:44:53.7204770Z raise child_exception_type(errno_num, err_msg, err_filename)
2025-09-16T13:44:53.7205350Z FileNotFoundError: [Errno 2] No such file or directory: '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/metallib'
```

I think it is because Metal is now a separate component in Xcode, and it is installed in a different place. See the output of:

```
$ xcrun -f metallib
/var/run/com.apple.security.cryptexd/mnt/com.apple.MobileAsset.MetalToolchain-v17.1.324.0.sHMV5s/Metal.xctoolchain/usr/bin/metallib
```