Create local C library implementation (1/2)

- 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: I91cddfb3229775f770ad781589670c57d347a154
diff --git a/include/stdlib/sys/ctype.h b/include/stdlib/sys/ctype.h
new file mode 100644
index 0000000..8e1ab6e
--- /dev/null
+++ b/include/stdlib/sys/ctype.h
@@ -0,0 +1,59 @@
+/*-
+ * Copyright (c) 1982, 1988, 1991, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ * (c) UNIX System Laboratories, Inc.
+ * All or some portions of this file are derived from material licensed
+ * to the University of California by American Telephone and Telegraph
+ * Co. or Unix System Laboratories, Inc. and are reproduced herein with
+ * the permission of UNIX System Laboratories, Inc.
+ *
+ * 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.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
+ *
+ * $FreeBSD$
+ */
+
+/*
+ * Portions copyright (c) 2009-2013, ARM Limited and Contributors.
+ * All rights reserved.
+ */
+
+#ifndef _SYS_CTYPE_H_
+#define	_SYS_CTYPE_H_
+
+#define isspace(c)	((c) == ' ' || ((c) >= '\t' && (c) <= '\r'))
+#define isascii(c)	(((c) & ~0x7f) == 0)
+#define isupper(c)	((c) >= 'A' && (c) <= 'Z')
+#define islower(c)	((c) >= 'a' && (c) <= 'z')
+#define isalpha(c)	(isupper(c) || islower(c))
+#define isdigit(c)	((c) >= '0' && (c) <= '9')
+#define isxdigit(c)	(isdigit(c) \
+			  || ((c) >= 'A' && (c) <= 'F') \
+			  || ((c) >= 'a' && (c) <= 'f'))
+#define isprint(c)	((c) >= ' ' && (c) <= '~')
+
+#define toupper(c)	((c) - 0x20 * (((c) >= 'a') && ((c) <= 'z')))
+#define tolower(c)	((c) + 0x20 * (((c) >= 'A') && ((c) <= 'Z')))
+
+#endif /* !_SYS_CTYPE_H_ */