unix: add linux mseal system call

The mseal system call was added in Linux 6.10.

See https://lwn.net/Articles/954936.

Change-Id: Ic812a5d784effbc1f362045ffeb6f7e50ee5f8bb
GitHub-Last-Rev: de3924e
GitHub-Pull-Request: #209
Reviewed-on: https://go-review.googlesource.com/c/sys/+/600518
Reviewed-by: Ian Lance Taylor <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Auto-Submit: Ian Lance Taylor <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>

Author: mauri870

unix/syscall_linux.go

@@ -2592,3 +2592,4 @@ func SchedGetAttr(pid int, flags uint) (*SchedAttr, error) {
 }
 
 //sys	Cachestat(fd uint, crange *CachestatRange, cstat *Cachestat_t, flags uint) (err error)
+//sys	Mseal(b []byte, flags uint) (err error)