* mangle.c (write_builtin_type): Support decimal float types.
	* g++.dg/dfp: New directory.
	* g++.dg/dg.exp: Prune tests in dfp directory.
	* g++.dg/dfp/dfp/exp: New.
	* g++.dg/dfp/mangle-mode.C: New test.

From-SVN: r152242