Remove empty newlines in #include blocks.

This makes clang-format useful on those.

Also add a bunch of forgotten transitive includes, which otherwise
prevented compilation.

src/core/settings.cpp

@@ -3,11 +3,8 @@
 // Refer to the license.txt file included.
 
 #include "settings.h"
-
 #include "audio_core/audio_core.h"
-
 #include "core/gdbstub/gdbstub.h"
-
 #include "video_core/video_core.h"
 
 namespace Settings {