Remove un-necessary referrer skip on popup windows

mount/nfs_export.cgi

@@ -2,7 +2,6 @@
 # nfs_export.cgi
 # Display a list of NFS exports on some host for the user to choose from
 
-$trust_unknown_referers = 1;
 require './mount-lib.pl';
 &ReadParse();
 &popup_header(&text('nfs_choose', &html_escape($in{'server'})));

mount/nfs_server.cgi

@@ -3,7 +3,6 @@
 # Called in a pop-up javascript window to display a list of known NFS
 # servers, generated by broadcasting on the NFS port
 
-$trust_unknown_referers = 1;
 require './mount-lib.pl';
 use Socket;
 &popup_header($text{'nfs_server'});

mount/smb_server.cgi

@@ -3,7 +3,6 @@
 # Called in a pop-up javascript window to display a list of known SMB
 # servers, by calling smbclient to request the browse list from some server
 
-$trust_unknown_referers = 1;
 require './mount-lib.pl';
 use Socket;
 &popup_header($text{'smb_choose'});