Import two patches from upstream in order to fix Modbus-RTU over RS485:
 1c5d969 Only set SER_RS485_ENABLED bit of existing RS485 settings
 91a1d74 Oops fix OR on RS485 settings (1c5d969)

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>

While at, also disable the build of the unit tests.

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

Although this version is marked 'unstable' by upstream, it's very
robust and stable. So give it a broader audience for testing.

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

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

I used the current version found in package feed, upgraded to the latest
stable upstream version, fixed the download url and added me as maintainer.

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