MFC r282067:

Integrate tools/regression/fifo into the FreeBSD test suite as tests/sys/fifo
and tools/regression/file into the FreeBSD test suite as tests/sys/file

Integrate tools/regression/fifo into the FreeBSD test suite as tests/sys/fifo
and tools/regression/file into the FreeBSD test suite as tests/sys/file

MFC after: 1 week

Integrate tools/regression/fifo into the FreeBSD test suite as tests/sys/fifo

Integrate more tests into the FreeBSD test suite from tools/regression, etc

Teach fifo_create regression test to also try to use mknod(2) to create
fifos, as this is required by the Single UNIX Specification, although
not currently implemented on FreeBSD.

While here, fix a bug in the directory timestamp checking test by
sleeping after querying the starting timestamp, rather than before.

Add fifo_create, a simple regression test for mkfifo(2).