build: Allow Objective-C++ code to be used

Change-Id: I63e5d866dd1dd04987572941d1c842e09c4494b4
diff --git a/.waf-tools/osx-frameworks.py b/.waf-tools/osx-frameworks.py
index 31c2bad..5366b72 100644
--- a/.waf-tools/osx-frameworks.py
+++ b/.waf-tools/osx-frameworks.py
@@ -1,7 +1,7 @@
 #! /usr/bin/env python
 # encoding: utf-8
 
-from waflib import Logs, Utils
+from waflib import Logs, Utils, TaskGen
 from waflib.Configure import conf
 
 OSX_SECURITY_CODE = '''
@@ -40,3 +40,8 @@
             Logs.warn("Compiling on OSX, but CoreFoundation, CoreServices, Security, or SystemConfiguration " +
                       "framework is not functional.")
             Logs.warn("The frameworks are known to work only with the Apple clang compiler")
+
+@TaskGen.extension('.mm')
+def m_hook(self, node):
+    """Alias .mm files to be compiled the same as .cpp files, gcc/clang will do the right thing."""
+    return self.create_compiled_task('cxx', node)