kbd: bump to 2.0.3 to fix musl build issue

kbd currently doesn't build against musl, due to some issues which
have already been fixed upstream. This commit therefore bumps to the
latest upstream version 2.0.3 to fix the musl build. In order to do
so, this commit also:

 - backports a patch that makes building tests optional, which allows
   to avoid a dependency on the check package

 - updates the libintl patch to work with the latest upstream

Fixes:

  http://autobuild.buildroot.net/results/535/5357953e763a1ac4f17332abac54ce2946629a41/



Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>