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>

ntripclient developer agency http://igs.bkg.bund.de/ does not reliably provide a source mirror with version naming.

Created a github repository to provide sources and allow contributions.

Signed-off-by: Nuno Goncalves <nunojpg@gmail.com>

Add missing `sys/select.h` include to `ntripclient.c` to provide
declarations for `struct timeval` and `fd_set` under musl.

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

Signed-off-by: Nuno Goncalves <nunojpg@gmail.com>