package/libnfs: add patch to fix musl build issue

Add a patch to fix build issues with the musl C library.

This patch fixes an autobuild issue when linking the mpd package
against libnfs. The header file libnfs.h uses `struct timeval` which is
defined in `<sys/time.h>` for POSIX systems. Unfortunately, upstream
only includes it conditionally, based on the system. Therefore, we
remove the check in the first patch.

Reported upstream:
https://github.com/sahlberg/libnfs/issues/272

Fixes:
http://autobuild.buildroot.org/results/452/4522014698b9fe50720a71b663e47a75805bcf54
http://autobuild.buildroot.org/results/b0a/b0a0c20ad1705e9fa7ba4a12eb9c182e8077ab0c
http://autobuild.buildroot.org/results/53c/53c87361923cc177de7889523b3d16ba6b1d3d0f
.. and more.

Previous patch: Changes requested
http://patchwork.ozlabs.org/patch/973605/



Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>