tweak support target

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@10658 d0543943-73ff-0310-b7d9-9358b9ac24b2

Makefile.am

@@ -454,7 +454,7 @@ support:
 	@cp support-d/.emacs ~
 	@cp support-d/.screenrc ~
 	@cp support-d/.bashrc ~
-	@sh support-d/install-cc-mode.sh
+	@test -f ~/.cc-mode-installed || sh support-d/install-cc-mode.sh && touch ~/.cc-mode-installed
 
 # Special targets