record-btrace, frame: supply target-specific unwinder

record-btrace, frame: supply target-specific unwinder

Supply a target-specific frame unwinder for the record-btrace target that does
not allow unwinding while replaying.

2013-02-11  Jan Kratochvil  <jan.kratochvil@redhat.com>
            Markus Metzger  <markus.t.metzger@intel.com>

gdb/
	* record-btrace.c: Include frame-unwind.h.
	(record_btrace_frame_unwind_stop_reason)
	(record_btrace_frame_this_id, record_btrace_frame_prev_register)
	(record_btrace_frame_sniffer, record_btrace_frame_unwind):
	New.
	(init_record_btrace_ops): Install it.