Fix lockdir not taking the value of backupdir

Thanks Claudio Kuenzler

virt-backup

@@ -48,7 +48,7 @@ $opts{backupdir} = '/var/lib/libvirt/backup';
 $opts{dumpcmd} = undef;
 # Lockdir is where locks will be held when backing up a VM. The default is to put the lock
 # in the backup dir of the VM, but in some situations, you want to put it elsewhere
-$opts{lockdir} = $opts{backupdir};
+$opts{lockdir} = undef;
 # Size of LVM snapshots (which will be used to backup VM with minimum downtime
 # if the VM is backed by LVM). If the LVM volume is thinly provisionned (thinp)
 # this parameter will be ignored
@@ -213,6 +213,8 @@ if (! -d $opts{backupdir} ){
     exit 1;
 }
 
+# If lockdir is not defined, take the same value as backupdir
+$opts{lockdir} ||= $opts{backupdir};
 # Lockdir, if defined, must also exist
 if (!-d $opts{lockdir}){
     print "$opts{lockdir} doesn't exist\n";