record: signal a record goto stop to front-ends

record: signal a record goto stop to front-ends

The "record goto" command does not indicate the stop to front-ends.  Instead,
it prints the new location directly.

Add a function to signal a normal stop to observers and have them print the new
location.  This function temporarily switches to the stopped thread.

We use the TARGET_WAITKIND_NO_RESUMED wait status for this purpose.  This should
result in a stop notification without giving a stop reason.  We could also
invent a new wait status but this doesn't seem necessary at this point.

Signed-off-by: Markus Metzger  <markus.t.metzger@intel.com>
gdb/
	* record.h (record_signal_goto_stop): New.
	* record.c (record_signal_goto_stop): New.

Change-Id: I0b196be68779f9e81abca78df5bc39e917023581