Replace unneded OC::needUpgrade with OCP method

lib/base.php

@@ -338,16 +338,6 @@ class OC {
 		die();
 	}
 
-	/**
-	 * check if the instance needs to perform an upgrade
-	 *
-	 * @return bool
-	 * @deprecated use \OCP\Util::needUpgrade() instead
-	 */
-	public static function needUpgrade() {
-		return \OCP\Util::needUpgrade();
-	}
-
 	/**
 	 * Checks if the version requires an update and shows
 	 * @param bool $showTemplate Whether an update screen should get shown

lib/public/backgroundjob.php

@@ -99,7 +99,7 @@ class BackgroundJob {
 	 * @since 4.5.0
 	 */
 	public static function addRegularTask($klass, $method) {
-		if (!\OC::needUpgrade()) {
+		if (!\OCP\Util::needUpgrade()) {
 			self::registerJob('OC\BackgroundJob\Legacy\RegularJob', array($klass, $method));
 			return true;
 		}