Fix possible memory leak in rescanLatestTimeLine()

[Yugo Nagata]

In rescanLatestTimeLine(), if a new target timeline is found, expectedTLEs is 
replaced with newExpectedTLEs that is newly allocated by readTimeLineHistory(),
and old expectedTLEs is released using list_free_deep().

However, if the current timeline is not part of the history of the new 
timeline, 
the function returns without using newExpectedTLEs, nor releasing it. I wonder 
this is a memory leak and it is better to release it, although the affect may
be not so much. 

I've attached the patch.

Regards,
Yugo Nagata

-- 
Yugo Nagata <nag...@sraoss.co.jp>

diff --git a/src/backend/access/transam/xlogrecovery.c b/src/backend/access/transam/xlogrecovery.c
index 178491f6f5..ec518d35e8 100644
--- a/src/backend/access/transam/xlogrecovery.c
+++ b/src/backend/access/transam/xlogrecovery.c
@@ -4157,6 +4157,7 @@ rescanLatestTimeLine(TimeLineID replayTLI, XLogRecPtr replayLSN)
 				(errmsg("new timeline %u is not a child of database system timeline %u",
 						newtarget,
 						replayTLI)));
+		list_free_deep(newExpectedTLEs);
 		return false;
 	}
 
@@ -4172,6 +4173,7 @@ rescanLatestTimeLine(TimeLineID replayTLI, XLogRecPtr replayLSN)
 						newtarget,
 						replayTLI,
 						LSN_FORMAT_ARGS(replayLSN))));
+		list_free_deep(newExpectedTLEs);
 		return false;
 	}