pkgfuncs.inc.php: Add missing global keyword

Use the global keyword to import "$AUR_LOCATION" in
add_package_comment().

Regression introduced in d3de6679

.
Signed-off-by: Lukas Fleischer <archlinux@cryptocrack.de>

web/lib/pkgfuncs.inc.php

@@ -212,6 +212,8 @@ function package_comments($pkgid, $dbh=NULL) {
 # Add a comment to a package page and send out appropriate notifications
 # TODO: Move notification logic to separate function where it belongs
 function add_package_comment($pkgid, $uid, $comment, $dbh=NULL) {
+	global $AUR_LOCATION;
+
 	if(!$dbh) {
 		$dbh = db_connect();
 	}