Remove igawk references as it's obsolete and not provided anymore.
Reported here: https://github.com/openwrt/packages/issues/5110
Fix package URL

Signed-off-by: Daniel Engberg <daniel.engberg.lists@pyret.net>

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

fix Makefile chmod (644)
replace MD5SUM with HASH
add PKG_MIRROR_HASH when PKG_SOURCE_PROTO:=git

(PKG_SOURCE_PROTO:=svn tarballs are not reproducible for now)

Signed-off-by: Etienne Champetier <champetier.etienne@gmail.com>

Coexists peacefully with busybox' awk.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>