on second thought, revise r12527 to use one, generic constant

PAGE_NAME, because that doesn't clutter the namespace as much.

include/init.php

@@ -417,7 +417,7 @@ switch ($sInitLocation) {
             // signout page will deal with users who aren't logged
             // in on its own; don't show error here
             //
-            if ( defined('PAGE_SIGNOUT') ) {
+            if ( defined('PAGE_NAME') && PAGE_NAME == 'signout' ) {
                 return;
             }
 

src/signout.php

@@ -12,7 +12,7 @@
  */
 
 /** This is the signout page */
-define('PAGE_SIGNOUT', 1);
+define('PAGE_NAME', 'signout');
 
 /**
  * Include the SquirrelMail initialization file.