[linux-lvm] lvm2_run: don't return uninitialized for _memlock_inc or _memlock_dec

[Jim Meyering <jim meyering net>]

I noticed a valid warning:

  lvmcmdlib.c:45: warning: 'ret' may be used uninitialized in this function

Sure, it's in nominally "Temporary" code (and code we'd rather
be rid of), but it's been over 6 months.
Any objection?