Eliminating one line of Perl 5.10 dependency

diff --git a/marc_cleanup b/marc_cleanup
index 04b9760..3b2c2ed 100755 (executable)
--- a/marc_cleanup
+++ b/marc_cleanup
@@ -603,7 +603,7 @@ sub initialize {
     show_trashhelp() if ($c->{trashhelp});
 
     # defaults
-    my $pfx = $c->{prefix} // "bibs";
+    my $pfx = defined($c->{prefix}) ? $c->{prefix} : "bibs";
     $c->{ricount} = 0;
     $c->{rocount} = 0;
     $c->{'renumber-tag'} = 903 unless defined $c->{'renumber-tag'};