swscale: Fix all cast qualifier warnings:

libswscale/swscale.c:2744:40: warning: to be safe all intermediate pointers in cast from ‘int16_t **’ to ‘const int16_t **’ must be ‘const’ qualified [-Wcast-qual]
libswscale/swscale.c:2745:41: warning: to be safe all intermediate pointers in cast from ‘int16_t **’ to ‘const int16_t **’ must be ‘const’ qualified [-Wcast-qual]
libswscale/swscale.c:2746:41: warning: to be safe all intermediate pointers in cast from ‘int16_t **’ to ‘const int16_t **’ must be ‘const’ qualified [-Wcast-qual]
libswscale/swscale.c:2747:78: 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/swscale.c

@@ -2741,10 +2741,10 @@ static int swScale(SwsContext *c, const uint8_t* src[],
         }
 
         {
-            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 **chrVSrcPtr= (const int16_t **) chrVPixBuf + 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 **chrVSrcPtr= (const int16_t **)(void*) chrVPixBuf + chrBufIndex + firstChrSrcY - lastInChrBuf + vChrBufSize;
+            const int16_t **alpSrcPtr= (CONFIG_SWSCALE_ALPHA && alpPixBuf) ? (const int16_t **)(void*) alpPixBuf + lumBufIndex + firstLumSrcY - lastInLumBuf + vLumBufSize : NULL;
             int16_t *vLumFilter= c->vLumFilter;
             int16_t *vChrFilter= c->vChrFilter;