Fix perl warnings https://sourceforge.net/p/webadmin/bugs/4907/

acl/acl-lib.pl

@@ -1672,8 +1672,9 @@ authenticate as, as array references.
 =cut
 sub get_unixauth
 {
+my ($miniserv) = @_;
 my @rv;
-my @ua = split(/\s+/, $_[0]->{'unixauth'});
+my @ua = $miniserv->{'unixauth'} ? split(/\s+/, $miniserv->{'unixauth'}) : ( );
 foreach my $ua (@ua) {
 	if ($ua =~ /^(\S+)=(\S+)$/) {
 		push(@rv, [ $1, $2 ]);

acl/edit_unix.cgi

@@ -30,7 +30,8 @@ my @webmins = map { [ $_->{'name'} ] }
 	       sort { $a->{'name'} cmp $b->{'name'} } &list_users();
 foreach my $ua (@unixauth, [ ], [ ]) {
 	$utable .= &ui_columns_row([
-		&ui_select("mode_$i", $ua->[0] eq "" ? 0 :
+		&ui_select("mode_$i", !defined($ua->[0]) ? 0 :
+				      $ua->[0] eq "" ? 0 :
 				      $ua->[0] eq "*" ? 1 :
 				      $ua->[0] =~ /^\@/ ? 2 : 3,
 			   [ [ 0, " " ],