dec_build_inter_predictors: don't return a void fn

split call of extend_and_predict() and return, fixes visual studio build
warning since:
0a80164 Move mc_buf to cut down size of MACROBLOCKD.

Change-Id: I7cdf712941ef773a07f038539cb8080dc27861cd

vp9/decoder/vp9_decodeframe.c

@@ -1985,7 +1985,7 @@ static void dec_build_inter_predictors(VP9Decoder *const pbi, MACROBLOCKD *xd,
       const int b_h = y1 - y0 + 1;
       const int border_offset = y_pad * 3 * b_w + x_pad * 3;
 
-      return extend_and_predict(buf_ptr1, buf_stride, x0, y0, b_w, b_h,
+      extend_and_predict(buf_ptr1, buf_stride, x0, y0, b_w, b_h,
                          frame_width, frame_height, border_offset,
                          dst, dst_buf->stride,
                          subpel_x, subpel_y,
@@ -1994,6 +1994,7 @@ static void dec_build_inter_predictors(VP9Decoder *const pbi, MACROBLOCKD *xd,
                          xd,
 #endif
                          w, h, ref, xs, ys);
+      return;
     }
   } else {
     // Wait until reference block is ready. Pad 7 more pixels as last 7