stdlib: add missing features to build PolarSSL

This patch adds the missing features to the C library included
in the Trusted Firmware to build PolarSSL:

  - strcasecmp() function
  - exit() function
  - sscanf()* function
  - time.h header file (and its dependencies)

* NOTE: the sscanf() function is not a real implementation. It just
returns the number of expected arguments by counting the number of
'%' characters present in the formar string. This return value is
good enough for PolarSSL because during the certificate parsing
only the return value is checked. The certificate validity period
is ignored.

Change-Id: I43bb3742f26f0bd458272fccc3d72a7f2176ab3d
diff --git a/include/stdlib/sys/timespec.h b/include/stdlib/sys/timespec.h
new file mode 100644
index 0000000..2505cef
--- /dev/null
+++ b/include/stdlib/sys/timespec.h
@@ -0,0 +1,63 @@
+/*-
+ * Copyright (c) 1982, 1986, 1993
+ *	The Regents of the University of California.  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.
+ * 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.
+ *
+ *	@(#)time.h	8.5 (Berkeley) 5/4/95
+ * from: FreeBSD: src/sys/sys/time.h,v 1.43 2000/03/20 14:09:05 phk Exp
+ *	$FreeBSD$
+ */
+
+#ifndef _SYS_TIMESPEC_H_
+#define _SYS_TIMESPEC_H_
+
+#include <sys/cdefs.h>
+#include <sys/_timespec.h>
+
+#if __BSD_VISIBLE
+#define	TIMEVAL_TO_TIMESPEC(tv, ts)					\
+	do {								\
+		(ts)->tv_sec = (tv)->tv_sec;				\
+		(ts)->tv_nsec = (tv)->tv_usec * 1000;			\
+	} while (0)
+#define	TIMESPEC_TO_TIMEVAL(tv, ts)					\
+	do {								\
+		(tv)->tv_sec = (ts)->tv_sec;				\
+		(tv)->tv_usec = (ts)->tv_nsec / 1000;			\
+	} while (0)
+
+#endif /* __BSD_VISIBLE */
+
+/*
+ * Structure defined by POSIX.1b to be like a itimerval, but with
+ * timespecs. Used in the timer_*() system calls.
+ */
+struct itimerspec {
+	struct timespec  it_interval;
+	struct timespec  it_value;
+};
+
+#endif /* _SYS_TIMESPEC_H_ */