cmake LIBREMIDI_CXX_HAS_WERROR_RETURN_TYPE examples

celtera/libremidi cmake/libremidi.deps.cmake :13 

check_cxx_compiler_flag(-Werror=return-type LIBREMIDI_CXX_HAS_WERROR_RETURN_TYPE)

celtera/libremidi cmake/libremidi.warnings.cmake :14 

target_compile_options(libremidi PRIVATE
      -Wall
      -Wextra
      $<$<BOOL:${LIBREMIDI_CI}>:-Werror>
      $<$<BOOL:${LIBREMIDI_CXX_HAS_WERROR_RETURN_TYPE}>:-Werror=return-type>
  )