gdb: use bool in the solib catchpoint area

gdb: use bool in the solib catchpoint area

Use bool instead of int in struct solib_catchpoint and in init_catchpoint &
related functions.

gdb/ChangeLog:

	* breakpoint.h (init_catchpoint): Change int parameter to bool.
	(add_solib_catchpoint): Likewise.
	* breakpoint.c (struct solib_catchpoint) <is_load>: Change type
	to bool.
	(add_solib_catchpoint): Change int parameter/variable to bool.
	(catch_load_or_unload): Likewise.
	(init_catchpoint): Likewise.
	(create_fork_vfork_event_catchpoint): Likewise.
	(catch_fork_command_1): Likewise.
	(catch_exec_command_1): Likewise.

Change-Id: I1faf4506e9109f3ccdd7229ba766dc7d77aa7aa0