try to make sure that ubuntu's openal target works

fggl/audio/openal/CMakeLists.txt

-find_package( OpenAL CONFIG REQUIRED )
-target_link_libraries( fggl PUBLIC OpenAL::OpenAL )
+find_package( OpenAL CONFIG )
+if ( NOT OpenAL_FOUND )
+    # ubuntu openal-soft package doesn't seem to have a config file
+    find_package( OpenAL REQUIRED )
+endif()
+
+if ( TARGET OpenAL::OpenAL )
+    target_link_libraries( fggl PUBLIC OpenAL::OpenAL )
+else()
+    target_link_libraries( fggl PUBLIC OpenAL )
+endif()
 
 target_sources(fggl
     PRIVATE