Adding explicit casts in yv12config.c.

This patch fixes c++ compiler errors.

Change-Id: I4d4b5af3bdaada101d753f3bc19819f5252b4e44

vpx_scale/generic/yv12config.c

@@ -60,7 +60,7 @@ int vp8_yv12_realloc_frame_buffer(YV12_BUFFER_CONFIG *ybf,
     const int frame_size = yplane_size + 2 * uvplane_size;
 
     if (!ybf->buffer_alloc) {
-      ybf->buffer_alloc = vpx_memalign(32, frame_size);
+      ybf->buffer_alloc = (uint8_t *)vpx_memalign(32, frame_size);
       ybf->buffer_alloc_sz = frame_size;
     }
 
@@ -180,12 +180,12 @@ int vp9_realloc_frame_buffer(YV12_BUFFER_CONFIG *ybf,
       // removed if border is totally removed.
       vpx_memset(fb->data, 0, fb->size);
 
-      ybf->buffer_alloc = yv12_align_addr(fb->data, 32);
+      ybf->buffer_alloc = (uint8_t *)yv12_align_addr(fb->data, 32);
     } else if (frame_size > ybf->buffer_alloc_sz) {
       // Allocation to hold larger frame, or first allocation.
       if (ybf->buffer_alloc)
         vpx_free(ybf->buffer_alloc);
-      ybf->buffer_alloc = vpx_memalign(32, frame_size);
+      ybf->buffer_alloc = (uint8_t *)vpx_memalign(32, frame_size);
       if (!ybf->buffer_alloc)
         return -1;