MinervaNeue has no sidebar, do not process this method

MinervaNeue doesn't show any sidebar, only MainMenu and
PagetActions menu. There is no need to call original
Skin::buildSidebar() as the result is not used.

Change-Id: Iec60491d4b45b7b6f6ba23525a4f6af08903bb31

includes/skins/SkinMinerva.php

@@ -973,6 +973,14 @@ class SkinMinerva extends SkinTemplate {
 		];
 	}
 
+	/**
+	 * Minerva skin do not have sidebar, there is no need to calculate that.
+	 * @return array
+	 */
+	public function buildSidebar() {
+		return [];
+	}
+
 	/**
 	 * Creates a history action: An icon that links to the mobile history page.
 	 *