CMake: Static build fails linking tests

[ePirat]

See this snippet from VideoLAN CI for the iOS build:

[46/46] Linking CXX executable tests/TestRenderer.app/TestRenderer
FAILED: tests/TestRenderer.app/TestRenderer 
: && /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -mios-version-min=9.0 -arch armv7 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.5.sdk -Werror=partial-availability -I/Users/videolanci/builds/x7XUHK5B/0/videolan/vlc/contrib/armv7-iphoneos/include -O2 -g -DNDEBUG -arch armv7 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.5.sdk -miphoneos-version-min=9.0 -Wl,-headerpad_max_install_names -mios-version-min=9.0 -mios-version-min=9.0 -arch armv7 -L/Users/videolanci/builds/x7XUHK5B/0/videolan/vlc/contrib/armv7-iphoneos/lib tests/CMakeFiles/TestRenderer.dir/TestRenderer.cpp.o -o tests/TestRenderer.app/TestRenderer  libspatialaudio.a  /Users/videolanci/builds/x7XUHK5B/0/videolan/vlc/contrib/armv7-iphoneos/lib/libmysofa.a && :
Undefined symbols for architecture armv7:
  "_inflate", referenced from:
      _gunzip in libmysofa.a(gunzip.c.o)
  "_inflateEnd", referenced from:
      _gunzip in libmysofa.a(gunzip.c.o)
  "_inflateInit_", referenced from:
      _gunzip in libmysofa.a(gunzip.c.o)
ld: symbol(s) not found for architecture armv7
clang: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.
make: *** [.spatialaudio] Error 1

[ePirat]

Looks like mysofa is not properly linked here, lacking its transitive dependencies like zlib.