Fix some of the things clang --analyze flagged

code/renderergl2/tr_main.c

@@ -1557,10 +1557,6 @@ static qboolean IsMirror( const drawSurf_t *drawSurf, int entityNum )
 		// translate the original plane
 		originalPlane.dist = originalPlane.dist + DotProduct( originalPlane.normal, tr.or.origin );
 	} 
-	else 
-	{
-		plane = originalPlane;
-	}
 
 	// locate the portal entity closest to this plane.
 	// origin will be the origin of the portal, origin2 will be