Add c++tools

Add c++tools

Part of our module implementation adds a sample mapper server, the
guts of which are used by the default in-process mapping of cc1plus.
Rather than add another executable to gcc/cp/, this creates a new
c++tools directory where this and any other c++ tools might live.
The toplevel changes are a subsequent commit, because ... git.

c++tools/ChangeLog:

	* Makefile.in: New.
	* config.h.in: New.
	* configure: New.
	* configure.ac: New.
	* resolver.cc: New.
	* resolver.h: New.
	* server.cc: New.