[binutils-gdb] Use std::string in break-catch-sig.c

[sergiodj+buildbot at sergiodj dot net]

*** TEST RESULTS FOR COMMIT 5809899dad253e2fefcb6f7ae57a6f43cfa4e3c5 ***

Author: Tom Tromey <tom@tromey.com>
Branch: master
Commit: 5809899dad253e2fefcb6f7ae57a6f43cfa4e3c5

Use std::string in break-catch-sig.c

This changes one spot in break-catch-sig.c to use std::string,
removing some cleanups.

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

	* break-catch-sig.c: Include <string>.
	(signal_catchpoint_print_one): Use std::string.