SHOW SLAVE STATUS AND GLOBAL READ LOCK.

Problem:
=======
SLAVE DEADLOCK CAUSED BY STOP SLAVE, SHOW SLAVE STATUS AND
GLOBAL READ LOCK

Analysis:
========
"FLUSH TABLES WITH READ LOCK" command blocks all DML and
DDL operations by taking "global read lock".  Hence when a
DML or DDL statement is received at slave, post "global read
lock" acquisition this operation will be blocked.  This 
causes slave sql thread to be blocked.

At this time when  STOP SLAVE command is issued in new slave
connection this command will acquire "LOCK_active_mi" and it
waits till the "sql thread" terminates.

Now in the first connection issue SHOW SLAVE STATUS command
which needs 'LOCK_active_mi' will be blocked till the above
lock is released by "STOP SLAVE".  Since "UNLOCK TABLES" can
only be done in first connection which is not possible any 
more, which causes a deadlock.

Fix:
===
Provide a new option to make the "STOP SLAVE" command to
timeout after specified number of seconds rather than
waiting for an year.

During testing the fix another deadlock issue was identified
with "STOP SLAVE" + "MTS" + "FLUSH TABLES WITH READ LOCK".
This was caused as "rli->run_lock" was moved as par of
BUG#13635612 fix to eliminate false suspects.  But since
this change is not necessary the "rli->run_lock" is moved
back to the appropriate place.