Mark constant structure member as const to avoid some warnings.

patch by Laurent Desnogues, laurent.desnogues gmail com

Originally committed as revision 13942 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/dct-test.c

@@ -68,7 +68,7 @@ extern void fdct_altivec (DCTELEM *block);
 
 
 struct algo {
-  char *name;
+  const char *name;
   enum { FDCT, IDCT } is_idct;
   void (* func) (DCTELEM *block);
   void (* ref)  (DCTELEM *block);