FileStore::_collection_rename: fix global replay guard

If the replay is being replayed, we might have already
performed the rename, skip it.  Also, we must set the
collection replay guard only after we have done the
rename.

Signed-off-by: Samuel Just <sam.just@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
(cherry picked from commit 870c474c5348831fcb13797d164f49682918fb30)
test/filestore/store_test: add test for 5723

Signed-off-by: Samuel Just <sam.just@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
(cherry picked from commit 37a4c4af54879512429bb114285bcb4c7c3488d5)

Conflicts:
	src/os/LFNIndex.cc
	src/test/filestore/store_test.cc
HashIndex: reset attr upon split or merge completion

A replay of an in progress merge or split might make
our counts unreliable.

Fixes: #5723
Signed-off-by: Samuel Just <sam.just@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
(cherry picked from commit 0dc3efdd885377a07987d868af5bb7a38245c90b)