tests: fix error handling around UNIX sockets

The wrong error code was checked on Windows, which may have caused all
UNIX sockets to be reported as error and the tests skipped.

Fixes #11258
Closes #11265

tests/server/util.c

@@ -819,23 +819,21 @@ int bind_unix_socket(curl_socket_t sock, const char *unix_socket,
     sau->sun_family = AF_UNIX;
     strncpy(sau->sun_path, unix_socket, sizeof(sau->sun_path) - 1);
     rc = bind(sock, (struct sockaddr*)sau, sizeof(struct sockaddr_un));
-    if(0 != rc && errno == EADDRINUSE) {
+    if(0 != rc && SOCKERRNO == EADDRINUSE) {
       struct_stat statbuf;
       /* socket already exists. Perhaps it is stale? */
       curl_socket_t unixfd = socket(AF_UNIX, SOCK_STREAM, 0);
       if(CURL_SOCKET_BAD == unixfd) {
-        error = SOCKERRNO;
-        logmsg("Error binding socket, failed to create socket at %s: (%d) %s",
-               unix_socket, error, strerror(error));
+        logmsg("Failed to create socket at %s: (%d)", unix_socket, SOCKERRNO);
+        perror("Error creating socket");
         return rc;
       }
       /* check whether the server is alive */
       rc = connect(unixfd, (struct sockaddr*)sau, sizeof(struct sockaddr_un));
-      error = errno;
+      error = SOCKERRNO;
       sclose(unixfd);
       if(ECONNREFUSED != error) {
-        logmsg("Error binding socket, failed to connect to %s: (%d) %s",
-               unix_socket, error, strerror(error));
+        logmsg("Failed to connect to %s: (%d)", unix_socket, error);
         return rc;
       }
       /* socket server is not alive, now check if it was actually a socket. */
@@ -852,8 +850,8 @@ int bind_unix_socket(curl_socket_t sock, const char *unix_socket,
       }
 #ifdef S_IFSOCK
       if((statbuf.st_mode & S_IFSOCK) != S_IFSOCK) {
-        logmsg("Error binding socket, failed to stat %s: (%d) %s",
-               unix_socket, error, strerror(error));
+        logmsg("Error binding socket, failed to stat %s: (%d)",
+               unix_socket, errno);
         return rc;
       }
 #endif