Fix problem with NT named pipes code (per e-mail thread).

sql/mysqld.cc:
  Should be mysql_unix_port (cut and paste error).

sql/mysqld.cc

@@ -1176,7 +1176,7 @@ static void server_init(void)
     
     pipe_name[sizeof(pipe_name)-1]= 0;		/* Safety if too long string */
     strxnmov(pipe_name, sizeof(pipe_name)-1, "\\\\.\\pipe\\",
-	     unix_socket, NullS);
+	     mysql_unix_port, NullS);
     bzero((char*) &saPipeSecurity, sizeof(saPipeSecurity) );
     bzero((char*) &sdPipeDescriptor, sizeof(sdPipeDescriptor) );
     if (!InitializeSecurityDescriptor(&sdPipeDescriptor,