cmake: disable UNIX_SYS by default for Android

This force disables SDL_OSS, SDL_ALSA, SDL_JACK, SDL_ESD,
SDL_PIPEWIRE, SDL_ARTS, SDL_NAS, SDL_SNDIO, SDL_LIBSAMPLERATE,
SDL_RPATH, SDL_CLOCK_GETTIME and SDL_X11.

CMakeLists.txt

@@ -178,7 +178,7 @@ elseif(CMAKE_SYSTEM_NAME MATCHES "Haiku.*")
 endif()
 
 # Don't mistake osx for unix
-if(UNIX AND NOT APPLE AND NOT RISCOS)
+if(UNIX AND NOT ANDROID AND NOT APPLE AND NOT RISCOS)
   set(UNIX_SYS ON)
 else()
   set(UNIX_SYS OFF)