Check for HOSTDELETED before h_Hold_r

Check for HOSTDELETED before h_Hold_r

A few places h_Hold_r a host and later drop and reacquire H_LOCK without
checking if the hostFlags contains HOSTDELETED. This can cause a race
with h_TossStuff_r where we later reference a host that is about to be
freed or already has been freed.

Add checks for HOSTDELETED in these places, and skip over the deleted
hosts.

FIXES 126454

Change-Id: I5a61831f5afdbc908b82e4cf63cf14a34a36e275
Reviewed-on: http://gerrit.openafs.org/1305
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>