Quote paths set to compiler flags

[mkniewallner]

Resolves #2750.

This quotes paths set to the compiler flags, to handle Python interpreters that are located in directories that have whitespaces.

Test plan

Ran the same commands as shared in #2750, and I was able to build the wheel:

$ uv python install 3.14
Installed Python 3.14.3 in 1.35s
 + cpython-3.14.3-macos-aarch64-none (python3.14)

$ uv build --wheel
...
adding 'uwsgi-2.1.dev0+0fa494ed.data/purelib/uwsgidecorators.py'
adding 'uwsgi-2.1.dev0+0fa494ed.data/scripts/uwsgi'
adding 'uwsgi-2.1.dev0+0fa494ed.dist-info/licenses/LICENSE'
adding 'uwsgi-2.1.dev0+0fa494ed.dist-info/METADATA'
adding 'uwsgi-2.1.dev0+0fa494ed.dist-info/WHEEL'
adding 'uwsgi-2.1.dev0+0fa494ed.dist-info/top_level.txt'
adding 'uwsgi-2.1.dev0+0fa494ed.dist-info/RECORD'
removing build/bdist.macosx-11.0-arm64/wheel
Successfully built dist/uwsgi-2.1.dev0+0fa494ed-cp314-cp314-macosx_11_0_arm64.whl

I've also run uWSGI server on a project by using uWSGI local dependency with the changes in this PR, and it worked.