mips noexec stack for security safety

BUG=168
TESTED=untested
Review URL: https://webrtc-codereview.appspot.com/994006

git-svn-id: http://libyuv.googlecode.com/svn/trunk@520 16f28f9a-4ce2-e073-06de-1de4eb20be90

README.chromium

@@ -1,6 +1,6 @@
 Name: libyuv
 URL: http://code.google.com/p/libyuv/
-Version: 519
+Version: 520
 License: BSD
 License File: LICENSE
 

include/libyuv/version.h

@@ -11,6 +11,6 @@
 #ifndef INCLUDE_LIBYUV_VERSION_H_  // NOLINT
 #define INCLUDE_LIBYUV_VERSION_H_
 
-#define LIBYUV_VERSION 519
+#define LIBYUV_VERSION 520
 
 #endif  // INCLUDE_LIBYUV_VERSION_H_  NOLINT

source/memcpy_mips.S

@@ -8,6 +8,11 @@
 #  in the file PATENTS.  All contributing project authors may
 #  be found in the AUTHORS file in the root of the source tree.
 #
+#if defined(__linux__) && defined(__ELF__)
+.section .note.GNU-stack,"",%progbits
+#endif
+  .text
+
   .globl  memcpy_MIPS;
   .align  2;
   .type   memcpy_MIPS,@function;