Added noexecstack markers for assembly files (webrtc issue 1172).

Webrtc builds on ios, linux, android and other major platforms passed. Didn't do chrome build test.
Review URL: https://webrtc-codereview.appspot.com/987004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3275 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/system_wrappers/interface/asm_defines.h

@@ -11,6 +11,10 @@
 #ifndef WEBRTC_SYSTEM_WRAPPERS_INTERFACE_ASM_DEFINES_H_
 #define WEBRTC_SYSTEM_WRAPPERS_INTERFACE_ASM_DEFINES_H_
 
+#if defined(__linux__) && defined(__ELF__)
+.section .note.GNU-stack,"",%progbits
+#endif
+
 // Define the macros used in ARM assembly code, so that for Mac or iOS builds
 // we add leading underscores for the function names.
 #ifdef __APPLE__
@@ -29,4 +33,6 @@ _\name:
 .endm
 #endif
 
+.text
+
 #endif  // WEBRTC_SYSTEM_WRAPPERS_INTERFACE_COMPILE_ASSERT_H_