[binutils-gdb] Use std::string in cp-namespace.c

[sergiodj+buildbot at sergiodj dot net]

*** TEST RESULTS FOR COMMIT 05d49c372d4689f8ca8baf4fdd32529ac40f297a ***

Author: Tom Tromey <tom@tromey.com>
Branch: master
Commit: 05d49c372d4689f8ca8baf4fdd32529ac40f297a

Use std::string in cp-namespace.c

This changes a few spots in cp-namespace.c to use std::string,
removing some cleanups.

2016-09-23  Tom Tromey  <tom@tromey.com>

	* cp-namespace.c: Include <string>.
	(cp_search_static_and_baseclasses)
	(cp_lookup_symbol_imports_or_template, find_symbol_in_baseclass):
	Use std::string.