C++-ify break-catch-sig

C++-ify break-catch-sig

This changes signal_catchpoint to be more of a C++ class, using
std::vector and updating the users.

ChangeLog
2017-07-22  Tom Tromey  <tom@tromey.com>

	* break-catch-sig.c (gdb_signal_type): Remove typedef.
	(struct signal_catchpoint) <signals_to_be_caught>: Now a
	std::vector.
	<catch_all>: Now a bool.
	(~signal_catchpoint): Remove.
	(signal_catchpoint_insert_location)
	(signal_catchpoint_remove_location)
	(signal_catchpoint_breakpoint_hit, signal_catchpoint_print_one)
	(signal_catchpoint_print_mention)
	(signal_catchpoint_print_recreate)
	(signal_catchpoint_explains_signal): Update.
	(create_signal_catchpoint): Change type of "filter" and
	"catch_all".
	(catch_signal_split_args): Return a std::vector.  Change type of
	"catch_all".
	(catch_signal_command): Update.