OpenWRT provides gcc but lacks make. So building foreign software is
difficult.

This patch provides GNU Make 4.1.

Built on Debian Jessie amd64.
Tested on TP-Link MR3020 (ar71xx/generic).

version 4:
	remove gnumake.h from the package
	We could package it in a separate make-dev package if really needed.

version 3:
	use Build/InstallDev to provide build time dependency

version 2:
	superfluous lines removed as suggested by Yousong Zhou

CC: Yousong Zhou <yszhou4tech@gmail.com>
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>