Add the M_PHI constant, contains an approximation of the golden ratio

irrational number.

Originally committed as revision 24439 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavutil/avutil.h

@@ -40,7 +40,7 @@
 #define AV_VERSION(a, b, c) AV_VERSION_DOT(a, b, c)
 
 #define LIBAVUTIL_VERSION_MAJOR 50
-#define LIBAVUTIL_VERSION_MINOR 22
+#define LIBAVUTIL_VERSION_MINOR 23
 #define LIBAVUTIL_VERSION_MICRO  0
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \

libavutil/mathematics.h

@@ -38,6 +38,9 @@
 #ifndef M_LOG2_10
 #define M_LOG2_10      3.32192809488736234787  /* log_2 10 */
 #endif
+#ifndef M_PHI
+#define M_PHI          1.61803398874989484820   /* phi / golden ratio */
+#endif
 #ifndef M_PI
 #define M_PI           3.14159265358979323846  /* pi */
 #endif