video_core/renderer_opengl: Remove unnecessary includes

Quite a few unused includes have built up over time, particularly on
core/memory.h. Removing these includes means the source files including
those files will no longer need to be rebuilt if they're changed, making
compilation slightly faster in this scenario.

src/video_core/renderer_opengl/gl_buffer_cache.cpp

@@ -7,7 +7,6 @@
 
 #include "common/alignment.h"
 #include "core/core.h"
-#include "core/memory.h"
 #include "video_core/renderer_opengl/gl_buffer_cache.h"
 #include "video_core/renderer_opengl/gl_rasterizer.h"