btrace: add replay position to btrace thread info

btrace: add replay position to btrace thread info

Add a branch trace instruction iterator pointing to the current replay position
to the branch trace thread info struct.

Free the iterator when btrace is cleared.

Start at the replay position for the instruction and function-call histories.

2014-01-16  Markus Metzger  <markus.t.metzger@intel.com>

	* btrace.h (replay) <replay>: New.
	(btrace_is_replaying): New.
	* btrace.c (btrace_clear): Free replay iterator.
	(btrace_is_replaying): New.
	* record-btrace.c (record_btrace_is_replaying): New.
	(record_btrace_info): Print insn number if replaying.
	(record_btrace_insn_history): Start at replay position.
	(record_btrace_call_history): Start at replay position.
	(init_record_btrace_ops): Init to_record_is_replaying.