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/times.h

@@ -0,0 +1,31 @@
+#ifndef	_SYS_TIMES_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+#define	_SYS_TIMES_H
+
+#include <_ansi.h>
+#include <machine/types.h>
+
+#ifndef __clock_t_defined
+typedef _CLOCK_T_ clock_t;
+#define __clock_t_defined
+#endif
+
+/*  Get Process Times, P1003.1b-1993, p. 92 */
+struct tms {
+	clock_t	tms_utime;		/* user time */
+	clock_t	tms_stime;		/* system time */
+	clock_t	tms_cutime;		/* user time, children */
+	clock_t	tms_cstime;		/* system time, children */
+};
+
+clock_t _EXFUN(times,(struct tms *));
+#ifdef _COMPILING_NEWLIB
+clock_t _EXFUN(_times,(struct tms *));
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+#endif	/* !_SYS_TIMES_H */