Turn all mutexes into critical sections

Removing all win32 mutexes and turning them into critical
sections, since mutexes in win32 are meant generally for
inter process communication, tend to be slower, and aren't
really needed for current purposes. Critical sections
are roughly equivalent to std::mutex in the c++ stl.

src/include/86box/vid_voodoo_common.h

@@ -491,7 +491,7 @@ typedef struct voodoo_t
 
         int force_blit_count;
         int can_blit;
-        lightmutex_t* force_blit_mutex;
+        mutex_t* force_blit_mutex;
 
         int use_recompiler;
         void *codegen_data;