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/wordexp.h

@@ -0,0 +1,53 @@
+/* Copyright (C) 2002, 2010 by  Red Hat, Incorporated. All rights reserved.
+ *
+ * Permission to use, copy, modify, and distribute this software
+ * is freely granted, provided that this notice is preserved.
+ */
+
+#ifndef _WORDEXP_H_
+#define _WORDEXP_H_
+
+#include <sys/types.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct _wordexp_t
+{
+  size_t we_wordc;	/* Count of words matched by words. */
+  char **we_wordv;	/* Pointer to list of expanded words. */
+  size_t we_offs;	/* Slots to reserve at the beginning of we_wordv. */
+};
+
+typedef struct _wordexp_t wordexp_t;
+
+#define	WRDE_DOOFFS	0x0001	/* Use we_offs. */
+#define	WRDE_APPEND	0x0002	/* Append to output from previous call. */
+#define	WRDE_NOCMD	0x0004	/* Don't perform command substitution. */
+#define	WRDE_REUSE	0x0008	/* pwordexp points to a wordexp_t struct returned from
+                                   a previous successful call to wordexp. */
+#define	WRDE_SHOWERR	0x0010	/* Print error messages to stderr. */
+#define	WRDE_UNDEF	0x0020	/* Report attempt to expand undefined shell variable. */
+
+enum {
+  WRDE_SUCCESS,
+  WRDE_NOSPACE,
+  WRDE_BADCHAR,
+  WRDE_BADVAL,
+  WRDE_CMDSUB,
+  WRDE_SYNTAX,
+  WRDE_NOSYS
+};
+
+/* Note: This implementation of wordexp requires a version of bash
+   that supports the --wordexp and --protected arguments to be present
+   on the system.  It does not support the WRDE_UNDEF flag. */
+int wordexp(const char *__restrict, wordexp_t *__restrict, int);
+void wordfree(wordexp_t *);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _WORDEXP_H_  */