Now that C++11 can be used in GCC, libcc1 can be changed to use
templates and type traits to handle unmarshalling all kinds of enums.

libcc1

	* marshall.hh (cc1_plugin::unmarshall): Use type traits.
	* marshall-cp.hh (cc1_plugin::unmarshall): Remove overloads.
	* marshall-c.hh: Remove.
	* libcc1plugin.cc: Update includes.
	* libcc1.cc: Update includes.