Propagate bind error for stream_socket_server()

When stream_socket_server() fails during bind(), we're currently only showing
"Unknown error" in the error message. Properly propagate this error for better
diagnostics.

Closes GH-21328

NEWS

@@ -145,6 +145,7 @@ PHP                                                                        NEWS
   . Allowed filtered streams to be casted as fd for select. (Jakub Zelenka)
   . Fixed bug GH-21221 (Prevent closing of innerstream of php://temp stream).
     (ilutov)
+  . Improved stream_socket_server() bind failure error reporting. (ilutov)
 
 - Zip:
   . Fixed ZipArchive callback being called after executor has shut down.

ext/standard/tests/network/stream_socket_server_bind_error.phpt

@@ -0,0 +1,19 @@
+--TEST--
+stream_socket_server() bind error
+--SKIPIF--
+<?php
+if (substr(PHP_OS, 0, 3) == 'WIN' ) {
+    die('skip not for Windows');
+}
+?>
+--FILE--
+<?php
+
+$server1 = stream_socket_server("tcp://0.0.0.0:0");
+$name = stream_socket_get_name($server1, false);
+$server2 = stream_socket_server("tcp://$name");
+fclose($server1);
+
+?>
+--EXPECTF--
+Warning: stream_socket_server(): Unable to connect to tcp://0.0.0.0:%d (Address %r(already )?%rin use) in %s on line %d

main/streams/xp_socket.c

@@ -699,8 +699,13 @@ static inline int php_tcp_sockop_bind(php_stream *stream, php_netstream_data_t *
 
 		parse_unix_address(xparam, &unix_addr);
 
-		return bind(sock->socket, (const struct sockaddr *)&unix_addr,
+		int result = bind(sock->socket, (const struct sockaddr *)&unix_addr,
 			(socklen_t) XtOffsetOf(struct sockaddr_un, sun_path) + xparam->inputs.namelen);
+		if (result == -1 && xparam->want_errortext) {
+			char errstr[256];
+			xparam->outputs.error_text = strpprintf(0, "%s", php_socket_strerror_s(errno, errstr, sizeof(errstr)));
+		}
+		return result;
 	}
 #endif