MFC r313483:

Fix setting birthtime in ZFS

sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c

• In zfs_freebsd_setattr, if the caller wants to set the birthtime,

	  set the bits that zfs_settattr expects

• In zfs_setattr, if XAT_CREATETIME is set, set xoa_createtime,

	  expected by zfs_xvattr_set.  The two levels of indirection seem
	  excessive, but it minimizes diffs vs OpenZFS.

• In zfs_setattr, check for overflow of va_birthtime (from delphij)

• Remove red herring in zfs_getattr

sys/cddl/contrib/opensolaris/uts/common/sys/vnode.h

• Un-booby-trap some macros

New tests are under review at https://github.com/pjd/pjdfstest/pull/6

Reviewed by: avg
MFC after: 3 weeks
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D9353