Layout_change is a reint operation, and it should be handled the
same as other reint operations, so that resent and replay can
work correctly.

Also replace the lock passed in ldlm_handle_enqueue0() with the
lock taken in mdt_layout_change(). This avoids taking lock again
in ldlm_handle_enqueue0(), and also makes replay eaiser. Note,
before replacing, the mode is downgraded from EX to CR, because
client only needs this mode, as can avoid unnecessary lock cancel
later.

Add missing resent reconstructor for REINT_RESYNC.

Signed-off-by: Lai Siyao <lai.siyao@whamcloud.com>
Change-Id: I328044dacbf18d03232c9bbb51271f6202e9b939
Reviewed-on: https://review.whamcloud.com/35465


Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>