10l: fix always false test: Binary & has lower precedence than ==

Originally committed as revision 12141 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/ppc/mpegvideo_altivec.c

@@ -603,7 +603,7 @@ extern void idct_add_altivec(uint8_t *dest, int line_size, int16_t *block);
 
 void MPV_common_init_altivec(MpegEncContext *s)
 {
-     if (mm_flags & MM_ALTIVEC == 0) return;
+     if (mm_flags & (MM_ALTIVEC == 0)) return;
 
     if (s->avctx->lowres==0)
     {