EX-3749 mdc: non blocking close and changelog release

EX-3749 mdc: non blocking close and changelog release

Use interruptible RPCs in mdc_close() and the llog client
functions. In chlg_release() send a SIGKILL to the changelog producer
thread to wake from waiting on any RPC responses. Add sanity.sh test
160r to verify.

Lustre-change: https://review.whamcloud.com/44842
Lustre-commit: 83e0eb2be4fa61344137b2f50724a1ca1dc532ae

Signed-off-by: John L. Hammond <jhammond@whamcloud.com>
Change-Id: I5f8b7cd839f5d6cf704ac07c7d583c45013921c4
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/44960
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Andreas Dilger <adilger@whamcloud.com>