Fix #22123 and #22124: some problems with mutex locks, also tweak to

how removing opengl textures from outside main thread is done so it
happens as part of the main loop.

source/blender/windowmanager/intern/wm_draw.c

@@ -48,6 +48,7 @@
 
 #include "ED_screen.h"
 
+#include "GPU_draw.h"
 #include "GPU_extensions.h"
 
 #include "WM_api.h"
@@ -695,6 +696,8 @@ void wm_draw_update(bContext *C)
 	wmWindowManager *wm= CTX_wm_manager(C);
 	wmWindow *win;
 	int drawmethod;
+
+	GPU_free_unused_buffers();
 	
 	for(win= wm->windows.first; win; win= win->next) {
 		if(win->drawmethod != U.wmdrawmethod) {

source/blender/windowmanager/intern/wm_init_exit.c

@@ -312,6 +312,7 @@ void WM_exit(bContext *C)
 	}
 	
 	GPU_buffer_pool_free(0);
+	GPU_free_unused_buffers();
 	GPU_extensions_exit();
 	
 //	if (copybuf) MEM_freeN(copybuf);