[x265] fix for old gcc

[Satoshi Nakagawa]

# HG changeset patch
# User Satoshi Nakagawa <nakagawa424 at oki.com>
# Date 1416475509 -32400
#      Thu Nov 20 18:25:09 2014 +0900
# Node ID c3a72e736de53af55fba25a5a5ba2da27722669f
# Parent  3649fabf90d348c51d7e155989d1bf629ec27f6e
fix for old gcc

diff -r 3649fabf90d3 -r c3a72e736de5 source/common/pixel.cpp
--- a/source/common/pixel.cpp	Thu Nov 20 14:27:53 2014 +0530
+++ b/source/common/pixel.cpp	Thu Nov 20 18:25:09 2014 +0900
@@ -175,7 +175,7 @@
 }
 
 template<int lx, int ly, class T1, class T2>
-int sse(T1* pix1, intptr_t stride_pix1, T2* pix2, intptr_t stride_pix2)
+int sse(const T1* pix1, intptr_t stride_pix1, const T2* pix2, intptr_t stride_pix2)
 {
     int sum = 0;
     int iTemp;