Remove VEC from breakpoint

Remove VEC from breakpoint

This removes a use of VEC from breakpoint.h, also removing the
now-unnecessary breakpoint_p typedef.

This patch fixes a latent memory leak in
find_matching_tracepoint_location, which neglected to free the vector
returned by all_tracepoints.

Tested by the buildbot.

gdb/ChangeLog
2018-07-03  Tom Tromey  <tom@tromey.com>

	* tracepoint.c (process_tracepoint_on_disconnect, start_tracing)
	(stop_tracing, tstatus_command)
	(find_matching_tracepoint_location, merge_uploaded_tracepoints)
	(print_one_static_tracepoint_marker): Update.
	* breakpoint.c (static_tracepoints_here, all_tracepoints): Return
	std::vector.
	* breakpoint.h (breakpoint_p): Remove typedef.  Don't declare
	VEC.
	(all_tracepoints, static_tracepoints_here): Return std::vector.