(svn r8605) -Codechange: [OSX] changed all objective C to objective C++

This will permanently solve the issue where compilation on OSX broke because C++ code was added to some header files

   -Note: (important if you develop mac specific code)
   taken from http://developer.apple.com/releasenotes/Cocoa/Objective-C++.html           
    gdb lacks an integrated C++ with Objective-C parser. This means that gdb won't be able to evaluate expressions that contain both C++ and Objective-C constructs.
    gdb assumes that the language for ".mm" files is C++.
    you can change it to objective C by typing: (gdb) set language objc 
    Mixing C++ and objective C has some limitation (see link for all of them)

src/unix.cpp

@@ -127,9 +127,9 @@ void ShowOSErrorBox(const char *buf)
 }
 
 #ifdef WITH_COCOA
-extern "C" void cocoaSetWorkingDirectory(void);
-extern "C" void cocoaSetupAutoreleasePool(void);
-extern "C" void cocoaReleaseAutoreleasePool(void);
+void cocoaSetWorkingDirectory(void);
+void cocoaSetupAutoreleasePool(void);
+void cocoaReleaseAutoreleasePool(void);
 #endif
 
 int CDECL main(int argc, char* argv[])