MFC r305358:

Update contrib/netbsd-tests with new content from NetBSD

This updates the snapshot from 09/30/2014 to 08/11/2016

This brings in a number of new testcases from upstream, most
notably:

- bin/cat
- lib/libc
- lib/msun
- lib/libthr
- usr.bin/sort

lib/libc/tests/stdio/open_memstream_test.c was moved to
lib/libc/tests/stdio/open_memstream2_test.c to accomodate
the new open_memstream test from NetBSD.

Tested on: amd64 (VMware fusion VM; various bare metal platforms); i386 (VMware fusion VM); make tinderbox