net: fix the kernel state name for TCP listen queue on FreeBSD

Fixes #23653.

Change-Id: Ic1e3c8f156ae576cfb5da1b4d082d4b12fae114f
Reviewed-on: https://go-review.googlesource.com/91317
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/net/sock_bsd.go

@@ -20,7 +20,7 @@ func maxListenerBacklog() int {
 	case "darwin":
 		n, err = syscall.SysctlUint32("kern.ipc.somaxconn")
 	case "freebsd":
-		n, err = syscall.SysctlUint32("kern.ipc.acceptqueue")
+		n, err = syscall.SysctlUint32("kern.ipc.soacceptqueue")
 	case "netbsd":
 		// NOTE: NetBSD has no somaxconn-like kernel state so far
 	case "openbsd":