Windows has no fcntl lock types, no O_ACCMODE and no x/sys/unix, so a
handful of constants kept weed/mount pinned to unix even though the code
using them is portable in-memory logic. Route them through per-OS shims
and give setBlksize a windows no-op.
The POSIX lock table now compiles on windows but stays unreachable:
WinFsp resolves byte-range locks in its own kernel driver, so nothing
will feed it there.
go.mod points at a go-fuse branch commit and needs repinning to a release
tag once that lands.
Chris Lu
b2e53d8035