wchar.h: improve wchar_t support in Bionic

Change-Id: Iffd41046fd0933c66542abf7627a1569522dfcb2
diff --git a/libc/wchar/wcsncmp.c b/libc/wchar/wcsncmp.c
new file mode 100644
index 0000000..86d7a51
--- /dev/null
+++ b/libc/wchar/wcsncmp.c
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 1989, 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.
+ */
+
+#include <sys/cdefs.h>
+#if 0
+#if defined(LIBC_SCCS) && !defined(lint)
+static char sccsid[] = "@(#)strncmp.c	8.1 (Berkeley) 6/4/93";
+__RCSID("$NetBSD: wcsncmp.c,v 1.3 2001/01/05 12:13:13 itojun Exp $");
+#endif /* LIBC_SCCS and not lint */
+#endif
+__FBSDID("$FreeBSD$");
+
+#include <wchar.h>
+
+int
+wcsncmp(const wchar_t *s1, const wchar_t *s2, size_t n)
+{
+
+	if (n == 0)
+		return (0);
+	do {
+		if (*s1 != *s2++) {
+			/* XXX assumes wchar_t = int */
+			return (*(const unsigned int *)s1 -
+			    *(const unsigned int *)--s2);
+		}
+		if (*s1++ == 0)
+			break;
+	} while (--n != 0);
+	return (0);
+}