Change iterate_over_breakpoints to take a function_view

This allows callers to pass in capturing lambdas.  Also changes the return
type to bool.

gdb/ChangeLog:

2019-10-15  Christian Biesinger  <cbiesinger@google.com>

	* breakpoint.c (iterate_over_breakpoints): Change function pointer
	to a gdb::function_view and return value to bool.
	* breakpoint.h (iterate_over_breakpoints): Likewise.
	* dummy-frame.c (pop_dummy_frame_bpt): Update.
	(pop_dummy_frame): Update.
	* guile/scm-breakpoint.c (bpscm_build_bp_list): Update.
	(gdbscm_breakpoints): Update.
	* python/py-breakpoint.c (build_bp_list): Update.
	(gdbpy_breakpoints): Update.
	* python/py-finishbreakpoint.c (bpfinishpy_detect_out_scope_cb):
	Update.
	(bpfinishpy_handle_stop): Update.
	(bpfinishpy_handle_exit): Update.
	* solib-svr4.c (svr4_update_solib_event_breakpoint): Update.
	(svr4_update_solib_event_breakpoints): Update.

Change-Id: Ia9de4deecae562a70a40f5cd49f5a74d64570251