Make fast bilinear scaler work again.

git-svn-id: file:///var/local/repositories/mplayer/trunk/libswscale@27543 b3059339-0415-0410-9bf9-f77b7e298cf2

swscale.c

@@ -54,6 +54,7 @@ untested special converters
   BGR24 -> YV12
 */
 
+#define _SVID_SOURCE //needed for MAP_ANONYMOUS
 #include <inttypes.h>
 #include <string.h>
 #include <math.h>