minor error fix

git-svn-id: http://haxe.googlecode.com/svn/trunk@6189 f16182fa-f095-11de-8f43-4547254af6c6
[cpp] Add extern enum generation

git-svn-id: http://haxe.googlecode.com/svn/trunk@6190 f16182fa-f095-11de-8f43-4547254af6c6