gdb: remove iterate_over_bp_locations function

gdb: remove iterate_over_bp_locations function

Remove it, change users (well, a single one) to use all_bp_locations.
This requires moving all_bp_locations to breakpoint.h to expose it.

gdb/ChangeLog:

	* breakpoint.h (iterate_over_bp_locations): Remove.  Update
	users to use all_bp_locations.
	(all_bp_locations): New.
	* breakpoint.c (all_bp_locations): Make non-static.
	(iterate_over_bp_locations): Remove.

Change-Id: Iaf1f716d6c2c5b2975579b3dc113a86f5d0975be