libc/tests: Enable fpsetround_basic which was never triggered since ported.

Reviewed by: imp
Pull Request: https://github.com/freebsd/freebsd-src/pull/1656

libc/tests: copy ieeefp tests out from contrib/netbsd-tests and rename them as FreeBSD test convention.

Reviewed by: imp
Pull Request: https://github.com/freebsd/freebsd-src/pull/1656