swscale: add missing HAVE_INLINE_ASM check.

The function called in this block is under HAVE_INLINE_ASM itself also.

libswscale/swscale.c

@@ -518,7 +518,7 @@ static int swScale(SwsContext *c, const uint8_t *src[],
         if (!enough_lines)
             break;  // we can't output a dstY line so let's try with the next slice
 
-#if HAVE_MMX
+#if HAVE_MMX && HAVE_INLINE_ASM
         updateMMXDitherTables(c, dstY, lumBufIndex, chrBufIndex,
                               lastInLumBuf, lastInChrBuf);
 #endif