Revert "listen(): improve POSIX compliance"

This reverts commit 76e6e4d72f.

Several programs in the tree use -1 instead of INT_MAX to use
the maximum value. Thanks to Eugene Grosbein for pointing this
out.

lib/libc/sys/listen.2

@@ -28,7 +28,7 @@
 .\"	From: @(#)listen.2	8.2 (Berkeley) 12/11/93
 .\" $FreeBSD$
 .\"
-.Dd October 11, 2022
+.Dd April 14, 2020
 .Dt LISTEN 2
 .Os
 .Sh NAME
@@ -106,13 +106,10 @@ specifies a hard limit on
 .Fa backlog ;
 if a value greater than
 .Va kern.ipc.soacceptqueue
-is specified,
+or less than zero is specified,
 .Fa backlog
 is silently forced to
 .Va kern.ipc.soacceptqueue .
-If a negative value is used,
-.Fa backlog
-is silently forced to 0.
 .Pp
 If the listen queue overflows, the kernel will emit a LOG_DEBUG syslog message.
 The
@@ -194,8 +191,3 @@ The original
 is still available but hidden from a
 .Xr sysctl 3
 -a output so that existing applications and scripts continue to work.
-To improve POSIX compliance, a negative
-.Fa backlog
-argument is handled the same as 0.
-This was introduced in
-.Fx 14.0 .

sys/kern/uipc_socket.c

@@ -1075,9 +1075,7 @@ solisten_proto(struct socket *so, int backlog)
 	so->so_options |= SO_ACCEPTCONN;
 
 listening:
-	if (backlog < 0)
-		backlog = 0;
-	if (backlog > somaxconn)
+	if (backlog < 0 || backlog > somaxconn)
 		backlog = somaxconn;
 	so->sol_qlimit = backlog;