avutil/buffer: Move USE_ATOMICS to thread.h to avoid it becoming out of sync with it

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavutil/buffer.c

@@ -25,8 +25,6 @@
 #include "mem.h"
 #include "thread.h"
 
-#define USE_ATOMICS !(HAVE_PTHREADS || HAVE_W32THREADS)
-
 AVBufferRef *av_buffer_create(uint8_t *data, int size,
                               void (*free)(void *opaque, uint8_t *data),
                               void *opaque, int flags)

libavutil/thread.h

@@ -26,6 +26,8 @@
 
 #if HAVE_PTHREADS || HAVE_W32THREADS || HAVE_OS2THREADS
 
+#define USE_ATOMICS 0
+
 #if HAVE_PTHREADS
 #include <pthread.h>
 #elif HAVE_OS2THREADS
@@ -43,6 +45,8 @@
 
 #else
 
+#define USE_ATOMICS 1
+
 #define AVMutex char
 
 #define ff_mutex_init(mutex, attr) (0)