[libc] Update libc.

1. Add POSIX termios implementation;
2. Add POSIX signals implementation;
3. Add stdio for each libc.

components/libc/compilers/newlib/libc.h

@@ -1,3 +1,28 @@
+/*
+ * File     : libc.h
+ * Brief    : gcc libc header file
+ *
+ * This file is part of RT-Thread RTOS
+ * COPYRIGHT (C) 2006 - 2017, RT-Thread Development Team
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2017/10/15     bernard      the first version
+ */
 #ifndef __RTT_LIBC_H__
 #define __RTT_LIBC_H__
 
@@ -12,6 +37,7 @@
 #define NANOSECOND_PER_TICK     (NANOSECOND_PER_SECOND  / RT_TICK_PER_SECOND)
 
 int libc_system_init(void);
+int libc_stdio_set_console(const char* device_name, int mode);
 
 /* some time related function */
 int libc_set_time(const struct timespec *time);