Hiding struct diff in *.c file.

Change-Id: Ia0dc05e530428af9ab5aa57e24f1115b0b4765d3

vp9/encoder/vp9_encodeframe.c

@@ -70,6 +70,12 @@ static const uint8_t VP9_VAR_OFFS[64] = {
   128, 128, 128, 128, 128, 128, 128, 128
 };
 
+typedef struct {
+  unsigned int sse;
+  int sum;
+  unsigned int var;
+} diff;
+
 static void get_sse_sum_8x8(const uint8_t *src, int src_stride,
                             const uint8_t *ref, int ref_stride,
                             unsigned int *sse, int *sum) {

vp9/encoder/vp9_encodeframe.h

@@ -20,12 +20,6 @@ struct macroblock;
 struct yv12_buffer_config;
 struct VP9_COMP;
 
-typedef struct {
-  unsigned int sse;
-  int sum;
-  unsigned int var;
-} diff;
-
 void vp9_setup_src_planes(struct macroblock *x,
                           const struct yv12_buffer_config *src,
                           int mi_row, int mi_col);