Re-add variable typo

… so that I can merge shreyasminocha’s PR, so they
get their commit in after so long. They apparently
noticed the type long before me, after all.

res/library/main.php

@@ -5,8 +5,8 @@
 //	Return the absolute path to the project's root.
 function get_project_root()
 {
-	return preg_replace("%" . $GLOBALS["root"] . ".*" . "%",
-				$GLOBALS["root"] . "/",
+	return preg_replace("%" . $GLOBALS["root_name"] . ".*" . "%",
+				$GLOBALS["root_name"] . "/",
 				getcwd());
 }