Add tsearch and friends, and a test program

tsearch is missing from windows. use the netbsd version as it's
license-compatible.

lib/roken/search.hin

@@ -0,0 +1,42 @@
+/*-
+ * Written by J.T. Conklin <jtc@netbsd.org>
+ * Public domain.
+ *
+ * $NetBSD: search.h,v 1.12 1999/02/22 10:34:28 christos Exp $
+ */
+
+#ifndef _rk_SEARCH_H_
+#define _rk_SEARCH_H_ 1
+
+#ifndef ROKEN_LIB_FUNCTION
+#ifdef _WIN32
+#define ROKEN_LIB_FUNCTION
+#define ROKEN_LIB_CALL     __cdecl
+#else
+#define ROKEN_LIB_FUNCTION
+#define ROKEN_LIB_CALL
+#endif
+#endif
+
+#include <sys/cdefs.h>
+#include <sys/types.h>
+
+typedef	enum {
+	preorder,
+	postorder,
+	endorder,
+	leaf
+} VISIT;
+
+ROKEN_CPP_START
+
+ROKEN_LIB_FUNCTION void	* ROKEN_LIB_CALL rk_tdelete(const void * __restrict, void ** __restrict,
+		 int (*)(const void *, const void *));
+ROKEN_LIB_FUNCTION void	* ROKEN_LIB_CALL rk_tfind(const void *, void * const *,
+	       int (*)(const void *, const void *));
+ROKEN_LIB_FUNCTION void	* ROKEN_LIB_CALL rk_tsearch(const void *, void **, int (*)(const void *, const void *));
+ROKEN_LIB_FUNCTION void	ROKEN_LIB_CALL rk_twalk(const void *, void (*)(const void *, VISIT, int));
+
+ROKEN_CPP_END
+
+#endif /* !_rk_SEARCH_H_ */