Introduce compiled_regex, eliminate make_regfree_cleanup

Introduce compiled_regex, eliminate make_regfree_cleanup

This patch replaces compile_rx_or_error and make_regfree_cleanup with
a class that wraps a regex_t.

gdb/ChangeLog:
2017-06-07  Pedro Alves  <palves@redhat.com>

	* Makefile.in (SFILES): Add gdb_regex.c.
	(COMMON_OBS): Add gdb_regex.o.
	* ada-lang.c (ada_add_standard_exceptions)
	(ada_add_exceptions_from_frame, name_matches_regex)
	(ada_add_global_exceptions, ada_exceptions_list_1): Change regex
	parameter type to compiled_regex.  Adjust.
	(ada_exceptions_list): Use compiled_regex.
	* break-catch-throw.c (exception_catchpoint::pattern): Now a
	std::unique_ptr<compiled_regex>.
	(exception_catchpoint::~exception_catchpoint): Remove regfree
	call.
	(check_status_exception_catchpoint): Adjust to use compiled_regex.
	(handle_gnu_v3_exceptions): Adjust to use compiled_regex.
	* breakpoint.c (solib_catchpoint::compiled): Now a
	std::unique_ptr<compiled_regex>.
	(solib_catchpoint::~solib_catchpoint): Remove regfree call.
	(check_status_catch_solib): Adjust to use compiled_regex.
	(add_solib_catchpoint): Adjust to use compiled_regex.
	* cli/cli-cmds.c (apropos_command): Use compiled_regex.
	* cli/cli-decode.c (apropos_cmd): Change regex parameter to
	compiled_regex reference.  Adjust to use it.
	* cli/cli-decode.h: Remove struct re_pattern_buffer forward
	declaration.  Include "gdb_regex.h".
	(apropos_cmd): Change regex parameter to compiled_regex reference.
	* gdb_regex.c: New file.
	* gdb_regex.h (make_regfree_cleanup, get_regcomp_error): Delete
	declarations.
	(class compiled_regex): New.
	* linux-tdep.c: Include "common/gdb_optional.h".
	(struct mapping_regexes): New, factored out from
	mapping_is_anonymous_p, and adjusted to use compiled_regex.
	(mapping_is_anonymous_p): Use mapping_regexes wrapped in a
	gdb::optional and remove cleanups.  Adjust to compiled_regex.
	* probe.c: Include "common/gdb_optional.h".
	(collect_probes): Use compiled_regex and gdb::optional and remove
	cleanups.
	* skip.c: Include "common/gdb_optional.h".
	(skiplist_entry::compiled_function_regexp): Now a
	gdb::optional<compiled_regex>.
	(skiplist_entry::compiled_function_regexp_is_valid): Delete field.
	(free_skiplist_entry): Remove regfree call.
	(compile_skip_regexp, skip_rfunction_p): Adjust to use
	compiled_regex and gdb::optional.
	* symtab.c: Include "common/gdb_optional.h".
	(search_symbols): Use compiled_regex and gdb::optional.
	* utils.c (do_regfree_cleanup, make_regfree_cleanup)
	(get_regcomp_error, compile_rx_or_error): Delete.  Some bits moved
	to gdb_regex.c.