FreeBSD: Add vop_standard_writecount_nomsync
https://cgit.freebsd.org/src/commit?id=3ffcfa599e29686cf2b3c1a6087408c37acaed78
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Ryan Moeller <freqlabs@FreeBSD.org>
Closes #12828