buffer_cache: Use boost::intrusive::set for caching

Instead of using boost::icl::interval_map for caching, use
boost::intrusive::set. interval_map is intended as a container where the
keys can overlap with one another; we don't need this for caching
buffers and a std::set-like data structure that allows us to search with
lower_bound is enough.

src/video_core/renderer_opengl/gl_buffer_cache.cpp

@@ -8,6 +8,7 @@
 
 #include "common/assert.h"
 #include "common/microprofile.h"
+#include "video_core/buffer_cache/buffer_cache.h"
 #include "video_core/engines/maxwell_3d.h"
 #include "video_core/rasterizer_interface.h"
 #include "video_core/renderer_opengl/gl_buffer_cache.h"

src/video_core/renderer_opengl/gl_fence_manager.cpp

@@ -4,6 +4,7 @@
 
 #include "common/assert.h"
 
+#include "video_core/renderer_opengl/gl_buffer_cache.h"
 #include "video_core/renderer_opengl/gl_fence_manager.h"
 
 namespace OpenGL {