libm.h needs attributes.h

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@22405 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavutil/libm.h

@@ -26,6 +26,7 @@
 
 #include <math.h>
 #include "config.h"
+#include "attributes.h"
 
 #if !HAVE_EXP2
 #undef exp2