package/libnfs: bump to version 3.0.0

package/libnfs: bump to version 3.0.0

Also add an patch from upstream to fix building libnfs with the musl C
library. This issue was introduced upstream between version 2.0.0 and
version 3.0.0.

Note, that upstreams commit message says it fixes a warning. However, as
musl is more strictly regarding missing headers it actually fixes the
build with musl.

Furthermore, the COPYING license file was changed in the way that it now
includes a clarification about the .x files being distributed under the
simplified BSD license. We already note in LIBNFS_LICENSE that the .x
files are BSD-2-Clause. So, updating the hash for this license file is
enough.

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>