Remove pointless code.

Originally committed as revision 11887 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/libxvidff.c

@@ -38,9 +38,7 @@
 #define BUFFER_CAT(x)               (&((x)[strlen(x)]))
 
 /* For PPC Use */
-#ifdef HAVE_ALTIVEC
 extern int has_altivec(void);
-#endif
 
 /**
  * Structure for the private XviD context.