'Undefined reference' when attempting to build with MSYS2 instructions

[RetroEdit]

It was confirmed to me that this is a known issue, but I don't think it's been filed here in the tracker. Essentially, mGBA's current instructions for building on Windows recommend using MSYS2. However, the build fails at the linking step for the final SDL and Qt executables. Below is a partial list of the 'Undefined references' errors that occur:

[ 53%] Linking C executable mgba-sdl.exe 
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/9.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: CMakeFiles/mgba-sdl.dir/objects.a(sdl-audio.c.obj):sdl-audio.c:(.text+0x8c): undefined reference to `mCoreSyncLockAudio' 
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/9.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: CMakeFiles/mgba-sdl.dir/objects.a(sdl-audio.c.obj):sdl-audio.c:(.text+0xad): undefined reference to `blip_set_rates' 
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/9.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: CMakeFiles/mgba-sdl.dir/objects.a(sdl-audio.c.obj):sdl-audio.c:(.text+0xc6): undefined reference to `blip_set_rates' 
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/9.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: CMakeFiles/mgba-sdl.dir/objects.a(sdl-audio.c.obj):sdl-audio.c:(.text+0xdb): undefined reference to `blip_samples_avail' 
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/9.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: CMakeFiles/mgba-sdl.dir/objects.a(sdl-audio.c.obj):sdl-audio.c:(.text+0xfb): undefined reference to `blip_read_samples' 
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/9.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: CMakeFiles/mgba-sdl.dir/objects.a(sdl-audio.c.obj):sdl-audio.c:(.text+0x113): undefined reference to `mCoreSyncConsumeAudio' 
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/9.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: CMakeFiles/mgba-sdl.dir/objects.a(sdl-audio.c.obj):sdl-audio.c:(.text+0x188): undefined reference to `GBAAudioCalculateRatio' 
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/9.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: CMakeFiles/mgba-sdl.dir/objects.a(sdl-audio.c.obj):sdl-audio.c:(.text+0x1c2): undefined reference to `blip_read_samples' 
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/9.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: CMakeFiles/mgba-sdl.dir/objects.a(sdl-audio.c.obj):sdl-audio.c:(.text+0x2ae): undefined reference to `mLog' 
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/9.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: CMakeFiles/mgba-sdl.dir/objects.a(sdl-audio.c.obj):sdl-audio.c:(.text+0x2f6): undefined reference to `mLog' 
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/9.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: CMakeFiles/mgba-sdl.dir/objects.a(sdl-audio.c.obj):sdl-audio.c:(.text.startup+0x13): undefined reference to `mLogGenerateCategory'