record-btrace: add to_wait and to_resume target methods.

record-btrace: add to_wait and to_resume target methods.

Add simple to_wait and to_resume target methods that prevent stepping when the
current replay position is not at the end of the execution log.

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

	* record-btrace.c (record_btrace_resume): New.
	(record_btrace_wait): New.
	(init_record_btrace_ops): Initialize to_wait and to_resume.