endian-conscious fix, courtesy of Sebastian Jedruszkiewicz

<elf -at- frogger.rules.pl>

Originally committed as revision 2107 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/common.h

@@ -1045,8 +1045,11 @@ static inline int ff_sqrt(int a)
  */
 static inline int ff_get_fourcc(const char *s){
     assert( strlen(s)==4 );
-    
+#ifndef WORDS_BIGENDIAN
     return (s[0]) + (s[1]<<8) + (s[2]<<16) + (s[3]<<24);
+#else
+    return (s[3]) + (s[2]<<8) + (s[1]<<16) + (s[0]<<24);
+#endif
 }
 
 #define MKTAG(a,b,c,d) (a | (b << 8) | (c << 16) | (d << 24))