revert parts of http://svnview.digium.com/svn/asterisk?view=revision&revision=432807 (clang support) as it breaks cross-compilation

--- Makefile
+++ Makefile
@@ -932,7 +932,7 @@
 	-@menuselect/nmenuselect menuselect.makeopts && (echo "menuselect changes saved!"; rm -f channels/h323/Makefile.ast main/asterisk) || echo "menuselect changes NOT saved!"
 
 # options for make in menuselect/
-MAKE_MENUSELECT=CC="$(BUILD_CC)" CXX="$(CXX)" LD="" AR="" RANLIB="" \
+MAKE_MENUSELECT=CC="$(BUILD_CC)" CXX="" LD="" AR="" RANLIB="" \
 		CFLAGS="$(BUILD_CFLAGS)" LDFLAGS="$(BUILD_LDFLAGS)" \
 		$(MAKE) -C menuselect CONFIGURE_SILENT="--silent"