libc: Fix alphasort() signature (and implementation).

The declaration for alphasort() in <dirent.h> used the deprecated:

  int alphasort(const void*, const void*);

while both Posix and GLibc use instead:

  int alphasort(const struct dirent** a, const struct dirent** b);

See: http://pubs.opengroup.org/onlinepubs/9699919799/functions/alphasort.html

This patch does the following:

- Update the declaration to match Posix/GLibc
- Get rid of the upstream BSD code which isn't compatible with the new
  signature.
- Implement a new trivial alphasort() with the right signature, and
  ensure that it uses strcoll() instead of strcmp().
- Remove Bionic-specific #ifdef .. #else .. #endif block in
  dirent_test.cpp which uses alphasort().

Even through strcoll() currently uses strcmp(), this does the right
thing in the case where we decide to update strcoll() to properly
implement locale-specific ordered comparison.

Change-Id: I4fd45604d8a940aaf2eb0ecd7d73e2f11c9bca96

libc/upstream-netbsd/libc/gen/alphasort.c

@@ -1,59 +0,0 @@
-/*	$NetBSD: alphasort.c,v 1.2 2009/03/01 19:59:55 christos Exp $	*/
-
-/*
- * Copyright (c) 1983, 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.
- * 3. 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 defined(LIBC_SCCS) && !defined(lint)
-#if 0
-static char sccsid[] = "@(#)scandir.c	8.3 (Berkeley) 1/2/94";
-#else
-__RCSID("$NetBSD: alphasort.c,v 1.2 2009/03/01 19:59:55 christos Exp $");
-#endif
-#endif /* LIBC_SCCS and not lint */
-
-#include "namespace.h"
-
-#include <assert.h>
-#include <dirent.h>
-#include <string.h>
-
-/*
- * Alphabetic order comparison routine for those who want it.
- */
-int
-alphasort(const void *d1, const void *d2)
-{
-
-	_DIAGASSERT(d1 != NULL);
-	_DIAGASSERT(d2 != NULL);
-
-	return (strcmp((*(const struct dirent *const *)d1)->d_name,
-	    (*(const struct dirent *const *)d2)->d_name));
-}