vp8: common: postproc: fix signed overflow of statement of (X +c) >= X when '-Werror=strict-overflow' is set.

Change-Id: I2f78417cc100973c732426f7b6bd10d7304a1a5f

vp8/common/postproc.c

@@ -214,6 +214,7 @@ static int q2mbl(int x)
     x = 50 + (x - 50) * 10 / 8;
     return x * x / 3;
 }
+
 void vp8_mbpost_proc_across_ip_c(unsigned char *src, int pitch, int rows, int cols, int flimit)
 {
     int r, c, i;
@@ -232,8 +233,8 @@ void vp8_mbpost_proc_across_ip_c(unsigned char *src, int pitch, int rows, int co
         /* 17 avoids valgrind warning - we buffer values in c in d
          * and only write them when we've read 8 ahead...
          */
-        for (i = cols; i<cols+17; i++)
+        for (i = 0; i < 17; i++)
-          s[i]=s[cols-1];
+          s[i+cols]=s[cols-1];
 
         for (i = -8; i <= 6; i++)
         {
@@ -264,7 +265,6 @@ void vp8_mbpost_proc_across_ip_c(unsigned char *src, int pitch, int rows, int co
     }
 }
 
-
 void vp8_mbpost_proc_down_c(unsigned char *dst, int pitch, int rows, int cols, int flimit)
 {
     int r, c, i;
@@ -284,8 +284,8 @@ void vp8_mbpost_proc_down_c(unsigned char *dst, int pitch, int rows, int cols, i
         /* 17 avoids valgrind warning - we buffer values in c in d
          * and only write them when we've read 8 ahead...
          */
-        for (i = rows; i < rows+17; i++)
+        for (i = 0; i < 17; i++)
-          s[i*pitch]=s[(rows-1)*pitch];
+          s[(i+rows)*pitch]=s[(rows-1)*pitch];
 
         for (i = -8; i <= 6; i++)
         {