Create local C library implementation (2/2)

- This change is split into two separate patches in order to
  simplify the history as interpreted by 'git'. The split is
  between the move/rename and addition of new files.
- Remove dependency on toolchain C library headers and functions in
  order to ensure behavioural compatibility between toolchains.
- Use FreeBSD as reference for C library implementation.
- Do not let GCC use default library include paths.
- Remove unused definitions in modified headers and implementations.
- Move C library files to 'lib/stdlib' and 'include/stdlib'.
- Break std.c functions out into separate files.

Change-Id: I3e3d8d992052264d2a02489034ae4c03bf0f5512
diff --git a/include/stdlib/sys/_stdint.h b/include/stdlib/sys/_stdint.h
new file mode 100644
index 0000000..d0f9249
--- /dev/null
+++ b/include/stdlib/sys/_stdint.h
@@ -0,0 +1,82 @@
+/*-
+ * Copyright (c) 2011 David E. O'Brien <obrien@FreeBSD.org>
+ * Copyright (c) 2001 Mike Barcroft <mike@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _SYS__STDINT_H_
+#define _SYS__STDINT_H_
+
+#ifndef _INT8_T_DECLARED
+typedef	__int8_t		int8_t;
+#define	_INT8_T_DECLARED
+#endif
+
+#ifndef _INT16_T_DECLARED
+typedef	__int16_t		int16_t;
+#define	_INT16_T_DECLARED
+#endif
+
+#ifndef _INT32_T_DECLARED
+typedef	__int32_t		int32_t;
+#define	_INT32_T_DECLARED
+#endif
+
+#ifndef _INT64_T_DECLARED
+typedef	__int64_t		int64_t;
+#define	_INT64_T_DECLARED
+#endif
+
+#ifndef _UINT8_T_DECLARED
+typedef	__uint8_t		uint8_t;
+#define	_UINT8_T_DECLARED
+#endif
+
+#ifndef _UINT16_T_DECLARED
+typedef	__uint16_t		uint16_t;
+#define	_UINT16_T_DECLARED
+#endif
+
+#ifndef _UINT32_T_DECLARED
+typedef	__uint32_t		uint32_t;
+#define	_UINT32_T_DECLARED
+#endif
+
+#ifndef _UINT64_T_DECLARED
+typedef	__uint64_t		uint64_t;
+#define	_UINT64_T_DECLARED
+#endif
+
+#ifndef _INTPTR_T_DECLARED
+typedef	__intptr_t		intptr_t;
+#define	_INTPTR_T_DECLARED
+#endif
+#ifndef _UINTPTR_T_DECLARED
+typedef	__uintptr_t		uintptr_t;
+#define	_UINTPTR_T_DECLARED
+#endif
+
+#endif /* !_SYS__STDINT_H_ */