While at, switch to xz-tarball.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

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>

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

u²pnpd announces a device as UPnP basic device on the
network so that an user could easily find it. It tries
to detect various system information automatically, however
everything can be overridden by UCI settings.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>