Update CompileDefinitions.cmake

USE_AUDIO is redundant in the presence of the already existent and more descriptive SUPPORT_MODULE_RAUDIO.

cmake/CompileDefinitions.cmake

@@ -11,7 +11,6 @@ endfunction()
 
 if(${CUSTOMIZE_BUILD})
     target_compile_definitions("raylib" PRIVATE EXTERNAL_CONFIG_FLAGS)
-    define_if("raylib" USE_AUDIO)
 
     foreach(FLAG IN LISTS CONFIG_HEADER_FLAGS)
         string(REGEX MATCH "([^=]+)=(.+)" _ ${FLAG})