snow: refactor code to work around a compiler bug in MSVC.

This fixes the compiler error "cannot convert from 'BlockNode' to
'int16_t'".

libavcodec/snowenc.c

@@ -1005,10 +1005,18 @@ static av_always_inline int check_block_inter(SnowContext *s, int mb_x, int mb_y
 static av_always_inline int check_4block_inter(SnowContext *s, int mb_x, int mb_y, int p0, int p1, int ref, int *best_rd){
     const int b_stride= s->b_width << s->block_max_depth;
     BlockNode *block= &s->block[mb_x + mb_y * b_stride];
-    BlockNode backup[4]= {block[0], block[1], block[b_stride], block[b_stride+1]};
+    BlockNode backup[4];
     unsigned value;
     int rd, index;
 
+    /* We don't initialize backup[] during variable declaration, because
+     * that fails to compile on MSVC: "cannot convert from 'BlockNode' to
+     * 'int16_t'". */
+    backup[0] = block[0];
+    backup[1] = block[1];
+    backup[2] = block[b_stride];
+    backup[3] = block[b_stride + 1];
+
     assert(mb_x>=0 && mb_y>=0);
     assert(mb_x<b_stride);
     assert(((mb_x|mb_y)&1) == 0);