Provide our own newlib libc

Newlib 2.2.0 w/ nan ofeatures, xtensa patches, locking
implementation.

Built from https://github.com/projectgus/newlib-xtensa
branch xtensa-2_2_0-lock
commit daa6ae40cdc8099f54c3e68a586fc1b906169c5a

For more details, see:
https://github.com/SuperHouse/esp-open-rtos/wiki/libc-configuration

Closes #1

libc/xtensa-lx106-elf/include/sys/timeb.h

@@ -0,0 +1,39 @@
+/* timeb.h -- An implementation of the standard Unix <sys/timeb.h> file.
+   Written by Ian Lance Taylor <ian@cygnus.com>
+   Public domain; no rights reserved.
+
+   <sys/timeb.h> declares the structure used by the ftime function, as
+   well as the ftime function itself.  Newlib does not provide an
+   implementation of ftime.  */
+
+#ifndef _SYS_TIMEB_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define _SYS_TIMEB_H
+
+#include <_ansi.h>
+#include <machine/types.h>
+
+#ifndef __time_t_defined
+typedef _TIME_T_ time_t;
+#define __time_t_defined
+#endif
+
+struct timeb
+{
+  time_t time;
+  unsigned short millitm;
+  short timezone;
+  short dstflag;
+};
+
+extern int ftime _PARAMS ((struct timeb *));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ! defined (_SYS_TIMEB_H) */