Make compiler-rt/trunk/lib/asan compileable with g++.

Patch by Timur Iskhodzhanov (timurrrr@google.com)

The double-extern thing is
http://llvm.org/bugs/show_bug.cgi?id=11869

And the #include <string[s].h> are only needed on Mac (see comments in
the original code)
and also including them might make strchr/index conflict with the g++
system headers (which don't follow the man pages, ouch!)

llvm-svn: 149129

compiler-rt/lib/asan/asan_interceptors.cc

@@ -26,8 +26,6 @@
 #include <ctype.h>
 #include <dlfcn.h>
 
-#include <string.h>
-#include <strings.h>
 #include <pthread.h>
 
 // To replace weak system functions on Linux we just need to declare functions
@@ -44,6 +42,10 @@
 // calls to our interceptors. We store pointers to system function f()
 // in __asan::real_f().
 #ifdef __APPLE__
+// Include the declarations of the original functions.
+#include <string.h>
+#include <strings.h>
+
 #include "mach_override/mach_override.h"
 #define WRAPPER_NAME(x) "wrap_"#x
 
@@ -307,7 +309,7 @@ void *WRAP(signal)(int signum, void *handler) {
 }
 
 extern "C"
-extern int (sigaction)(int signum, const void *act, void *oldact);
+int (sigaction)(int signum, const void *act, void *oldact);
 
 extern "C"
 int WRAP(sigaction)(int signum, const void *act, void *oldact) {

compiler-rt/lib/asan/asan_internal.h

@@ -31,6 +31,10 @@
 #endif
 #endif
 
+#if !defined(__has_feature)
+#define __has_feature(x) 0
+#endif
+
 #if defined(__has_feature) && __has_feature(address_sanitizer)
 # error "The AddressSanitizer run-time should not be"
         " instrumented by AddressSanitizer"