* Add POSIX byte-range lock table for FUSE mount
Implement PosixLockTable with per-inode range lock tracking supporting:
- Shared (F_RDLCK) and exclusive (F_WRLCK) byte-range locks
- Conflict detection across different lock owners
- Lock coalescing for adjacent/overlapping same-owner same-type locks
- Lock splitting on partial-range unlock
- Blocking waiter support for SetLkw with cancellation
- Owner-based cleanup for Release
* Wire POSIX lock handlers into FUSE mount
Implement GetLk, SetLk, SetLkw on WFS delegating to PosixLockTable.
Add posixLocks field to WFS and initialize in constructor.
Clean up locks on Release via ReleaseOwner using ReleaseIn.LockOwner.
Remove ENOSYS stubs from weedfs_unsupported.go.
* Enable POSIX and flock lock capabilities in FUSE mount
Set EnableLocks: true in mount options to advertise
CAP_POSIX_LOCKS and CAP_FLOCK_LOCKS during FUSE INIT.
* Avoid thundering herd in lock waiter wake-up
Replace broadcast-all wakeWaiters with selective wakeEligibleWaiters
that checks each waiter's requested lock against remaining held locks.
Only waiters whose request no longer conflicts are woken; others stay
queued. Store the requested lockRange in each lockWaiter to enable this.
* Fix uint64 overflow in adjacency check for lock coalescing
Guard h.End+1 and lk.End+1 with < ^uint64(0) checks so that
End == math.MaxUint64 (EOF) does not wrap to 0 and falsely merge
non-adjacent locks.
* Add test for non-adjacent ranges with gap not being coalesced
Chris Lu