GPU: Add GC to FBOs and UBOs and centralize all GCs

GPUFrameBuffers were being free when no context was attached or in the
wrong gl context. This make sure this does not happen again.

You can now safely free any gl resource from any thread (well as long as
it's not used anymore!).

source/blender/gpu/intern/gpu_batch.c

@@ -32,12 +32,11 @@
 
 #include "GPU_batch.h"
 #include "GPU_batch_presets.h"
-#include "GPU_buffer_id.h"
 #include "GPU_matrix.h"
 #include "GPU_shader.h"
-#include "GPU_vertex_array_id.h"
 
 #include "gpu_batch_private.h"
+#include "gpu_context_private.h"
 #include "gpu_primitive_private.h"
 #include "gpu_shader_private.h"