avcodec/cos_tablegen: use M_PI instead of actual literal

Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>

libavcodec/cos_tablegen.c

@@ -24,6 +24,8 @@
 #include <string.h>
 #include <math.h>
 
+#include "libavutil/mathematics.h"
+
 #define BITS 16
 #define FLOATFMT "%.18e"
 #define FIXEDFMT "%6d"
@@ -61,7 +63,7 @@ int main(int argc, char *argv[])
     printf("#include \"libavcodec/%s\"\n", do_sin ? "rdft.h" : "fft.h");
     for (i = 4; i <= BITS; i++) {
         int m = 1 << i;
-        double freq = 2*3.14159265358979323846/m;
+        double freq = 2*M_PI/m;
         printf("%s(%i) = {\n   ", do_sin ? "SINTABLE" : "COSTABLE", m);
         for (j = 0; j < m/2 - 1; j++) {
             int idx = j > m/4 ? m/2 - j : j;