viced: Set HWHO_INPROGRESS in CheckHost_r

viced: Set HWHO_INPROGRESS in CheckHost_r

When we are probing a host in CheckHost_r, set the HWHO_INPROGRESS
flag on the host, so other threads know that the host is locked while
we are waiting for a probe response, and the h_threadquota mechanism
can work correctly.

Change-Id: I37e3b37ea98d8d42578bf85a3b5aaaff4c4a7331
Reviewed-on: http://gerrit.openafs.org/4126
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>