LU-8624 osc: hung in osc_destroy()

LU-8624 osc: hung in osc_destroy()

cl_destroy_in_flight becomes < 0 because the
osc_can_send_destroy() won't increment
cl_destroy_in_flight if l_wait_event() gets
interrupted by a signal, but the request will
still be sent and the request's interpret
function will decrease the counter.

Don't send OST_DESTROY request on signal
and return -EINTR.

Seagate-bug-id: MRP-3834
Change-Id: Ie725e501909095b8cd853287b9a43feb1f89ddb5
Signed-off-by: Andriy Skulysh <andriy.skulysh@seagate.com>
Reviewed-on: https://review.whamcloud.com/22588
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>