lwp: Fix possible memory leak from scan-build

lwp: Fix possible memory leak from scan-build

It is possible for LWP_CreateProcess to return early. When it does, it
should free up any memory it allocated before leaving scope.

Change-Id: Ib5644d36dc01bbac33804f4a039661ce2c78969d
Reviewed-on: https://gerrit.openafs.org/13080
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Marcio Brito Barbosa <mbarbosa@sinenomine.net>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>