chore: updates build to allow portaudio to be dynamically linked

[rektdeckard]

Homebrew maintainers did not like us vendoring portaudio when a formula exists for it (albeit dynamically linking the library).

For homebrew builds and whenever portaudio_system tag is specified, we do not use the vendored portaudio copy and instead link it dynamically. For all other builds, we continue to use the vendored copy and produce a unity build. This lets us keep other build targets portable.

Standard, vendored build:

> otool -L ./bin/lk
./bin/lk:
        /System/Library/Frameworks/CoreAudio.framework/Versions/A/CoreAudio (compatibility version 1.0.0, current version 1.0.0)
        /System/Library/Frameworks/AudioToolbox.framework/Versions/A/AudioToolbox (compatibility version 1.0.0, current version 1000.0.0)
        /System/Library/Frameworks/AudioUnit.framework/Versions/A/AudioUnit (compatibility version 1.0.0, current version 1.0.0)
        /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 5026.5.4)
        /System/Library/Frameworks/CoreServices.framework/Versions/A/CoreServices (compatibility version 1.0.0, current version 1226.0.0)
        /usr/lib/libresolv.9.dylib (compatibility version 1.0.0, current version 1.0.0)
        /System/Library/Frameworks/Security.framework/Versions/A/Security (compatibility version 1.0.0, current version 61901.120.67)
        /usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 228.0.0)
        /usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 2100.43.0)
        /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1356.0.0)

With -tags portaudio_system:

> otool -L ./bin/lk
./bin/lk:
        /opt/homebrew/opt/portaudio/lib/libportaudio.2.dylib (compatibility version 3.0.0, current version 3.0.0)
        /System/Library/Frameworks/CoreAudio.framework/Versions/A/CoreAudio (compatibility version 1.0.0, current version 1.0.0)
        /System/Library/Frameworks/AudioToolbox.framework/Versions/A/AudioToolbox (compatibility version 1.0.0, current version 1000.0.0)
        /System/Library/Frameworks/AudioUnit.framework/Versions/A/AudioUnit (compatibility version 1.0.0, current version 1.0.0)
        /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 5026.5.4)
        /System/Library/Frameworks/CoreServices.framework/Versions/A/CoreServices (compatibility version 1.0.0, current version 1226.0.0)
        /usr/lib/libresolv.9.dylib (compatibility version 1.0.0, current version 1.0.0)
        /System/Library/Frameworks/Security.framework/Versions/A/Security (compatibility version 1.0.0, current version 61901.120.67)
        /usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 228.0.0)
        /usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 2100.43.0)
        /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1356.0.0)

[theomonnom]

Oh interesting that brew is pushing against static linking.
Thanks @rektdeckard