improve Makefile handling of git checkouts with missing lib/ and config.mak
improve Makefile handling of git checkouts with missing lib/ and config.mak

chardi/musl,chardi/musl,davidlazar/musl,davidlazar/musl,rofl0r/musl-old,chneukirchen/musl-chris2,chardi/musl,chneukirchen/musl-chris2,rofl0r/musl-old