swscale_mmx: Fix cast qualifier warnings:

libswscale/x86/swscale_mmx.c:131:36: warning: to be safe all intermediate pointers in cast from ‘int16_t **’ to ‘const int16_t **’ must be ‘const’ qualified [-Wcast-qual]
libswscale/x86/swscale_mmx.c:132:37: warning: to be safe all intermediate pointers in cast from ‘int16_t **’ to ‘const int16_t **’ must be ‘const’ qualified [-Wcast-qual]
libswscale/x86/swscale_mmx.c:133:74: warning: to be safe all intermediate pointers in cast from ‘int16_t **’ to ‘const int16_t **’ must be ‘const’ qualified [-Wcast-qual]
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libswscale/x86/swscale_mmx.c

@@ -128,9 +128,9 @@ void updateMMXDitherTables(SwsContext *c, int dstY, int lumBufIndex, int chrBufI
         c->greenDither= ff_dither4[dstY&1];
     c->redDither= ff_dither8[(dstY+1)&1];
     if (dstY < dstH - 2) {
-        const int16_t **lumSrcPtr= (const int16_t **) lumPixBuf + lumBufIndex + firstLumSrcY - lastInLumBuf + vLumBufSize;
-        const int16_t **chrUSrcPtr= (const int16_t **) chrUPixBuf + chrBufIndex + firstChrSrcY - lastInChrBuf + vChrBufSize;
-        const int16_t **alpSrcPtr= (CONFIG_SWSCALE_ALPHA && alpPixBuf) ? (const int16_t **) alpPixBuf + lumBufIndex + firstLumSrcY - lastInLumBuf + vLumBufSize : NULL;
+        const int16_t **lumSrcPtr= (const int16_t **)(void*) lumPixBuf + lumBufIndex + firstLumSrcY - lastInLumBuf + vLumBufSize;
+        const int16_t **chrUSrcPtr= (const int16_t **)(void*) chrUPixBuf + chrBufIndex + firstChrSrcY - lastInChrBuf + vChrBufSize;
+        const int16_t **alpSrcPtr= (CONFIG_SWSCALE_ALPHA && alpPixBuf) ? (const int16_t **)(void*) alpPixBuf + lumBufIndex + firstLumSrcY - lastInLumBuf + vLumBufSize : NULL;
         int i;
         if (flags & SWS_ACCURATE_RND) {
             int s= APCK_SIZE / 8;