swscale: #include "libavutil/mathematics.h"

this file uses the M_PI macro since
4e74187db2, so include the correct header
directly.

Signed-off-by: Reinhard Tartler <siretart@tauware.de>

libswscale/utils.c

@@ -43,6 +43,7 @@
 #include "libavutil/cpu.h"
 #include "libavutil/avutil.h"
 #include "libavutil/bswap.h"
+#include "libavutil/mathematics.h"
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"