LU-16893 libcfs: Remove force_sig usage from lfsck

LU-16893 libcfs: Remove force_sig usage from lfsck

The lfsck pool of kernel threads uses force_sig() to signal
the worker threads to stop. A signal is used here as the
lfsck workers may be waiting in various, and possibly
nested, states.

As force_sig() has been removed let us simply enable SIGINT
to be passed to the worker threads using send_sig().

Test-parameters: testlist=sanity-lfsck,lfsck-performance
HPE-bug-id: LUS-11670
Fixes: db9f9543ec ("LU-12634 libcfs: force_sig() removed task parameter")
Signed-off-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Change-Id: Ibf6a67f43687960b3eff9cb9a7c7dc8b1be1da63
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/51470
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>