cmake HAVE_FMA examples

spotify/pedalboard vendors/fftw3/CMakeLists.txt :185 

unset (HAVE_FMA CACHE)

spotify/pedalboard vendors/fftw3/CMakeLists.txt :186 

unset (HAVE_FMA)

spotify/pedalboard vendors/fftw3/CMakeLists.txt :187 

check_c_compiler_flag (${FLAG} HAVE_FMA)