remote: fix UNIX socket path being incorrectly built for libvirtd

As a result of changes in

      commit d5f0c1b6
      Author: Daniel P. Berrangé <berrange@redhat.com>
      Date:   Thu Jul 18 12:30:22 2019 +0100

        remote: stop trying to print help as giant blocks of text

The socket path built would be libvirt//var/run/libvirt-sock
instead of /var/run/libvirt/libvirt-sock. Fortunately this only
affects users who have set the 'unix_sock_dir' config parameter
in /etc/libvirt/libvirtd.conf, which is pretty rare/unusual.
Signed-off-by: Neater <=@eater.me>

Exception made for the psuedonym above since patch is considered
trivial & thus non-copyrightable material.
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

src/remote/remote_daemon.c

@@ -226,14 +226,14 @@ daemonUnixSocketPaths(struct daemonConfig *config,
 
     if (config->unix_sock_dir) {
         if (virAsprintf(sockfile, "%s/%s-sock",
-                        SOCK_PREFIX, config->unix_sock_dir) < 0)
+                        config->unix_sock_dir, SOCK_PREFIX) < 0)
             goto cleanup;
 
         if (privileged) {
             if (virAsprintf(rosockfile, "%s/%s-sock-ro",
-                            SOCK_PREFIX, config->unix_sock_dir) < 0 ||
+                            config->unix_sock_dir, SOCK_PREFIX) < 0 ||
                 virAsprintf(admsockfile, "%s/%s-admin-sock",
-                            SOCK_PREFIX, config->unix_sock_dir) < 0)
+                            config->unix_sock_dir, SOCK_PREFIX) < 0)
                 goto cleanup;
         }
     } else {