New additions/bug fixes required/found when porting perf.

New functions:
	tfind
	tsearch
	tdelete
	twalk
	tdestroy (GNU extension)

Bug fix: the current implementation for realpath would crash
	if the second argument (resolved_path) is NULL.

New headers:
	ar.h
	search.h

Change-Id: Ib6c1e42fc186a6d597a6e5a9692b16acaa155804
diff --git a/libc/bionic/tfind.c b/libc/bionic/tfind.c
new file mode 100644
index 0000000..7e2bb0c
--- /dev/null
+++ b/libc/bionic/tfind.c
@@ -0,0 +1,48 @@
+/*	$NetBSD: tfind.c,v 1.2 1999/09/16 11:45:37 lukem Exp $	*/
+
+/*
+ * Tree search generalized from Knuth (6.2.2) Algorithm T just like
+ * the AT&T man page says.
+ *
+ * The node_t structure is for internal use only, lint doesn't grok it.
+ *
+ * Written by reading the System V Interface Definition, not the code.
+ *
+ * Totally public domain.
+ */
+
+#include <sys/cdefs.h>
+#if 0
+#if defined(LIBC_SCCS) && !defined(lint)
+__RCSID("$NetBSD: tfind.c,v 1.2 1999/09/16 11:45:37 lukem Exp $");
+#endif /* LIBC_SCCS and not lint */
+#endif
+__FBSDID("$FreeBSD: release/9.0.0/lib/libc/stdlib/tfind.c 108694 2003-01-05 02:43:18Z tjr $");
+
+#define _SEARCH_PRIVATE
+#include <stdlib.h>
+#include <search.h>
+
+/* find a node, or return 0 */
+void *
+tfind(vkey, vrootp, compar)
+	const void *vkey;		/* key to be found */
+	void * const *vrootp;		/* address of the tree root */
+	int (*compar)(const void *, const void *);
+{
+	node_t **rootp = (node_t **)vrootp;
+
+	if (rootp == NULL)
+		return NULL;
+
+	while (*rootp != NULL) {		/* T1: */
+		int r;
+
+		if ((r = (*compar)(vkey, (*rootp)->key)) == 0)	/* T2: */
+			return *rootp;		/* key found */
+		rootp = (r < 0) ?
+		    &(*rootp)->llink :		/* T3: follow left branch */
+		    &(*rootp)->rlink;		/* T4: follow right branch */
+	}
+	return NULL;
+}