[IMPORT] import ebtree v5.0 into directory ebtree/

We needed to upgrade ebtree to v5.0 to support string indexing,
and it was getting very painful to have it split across 2 dirs
and to have to patch it. Now we just have to copy the .c and .h
files to the right place.
diff --git a/ebtree/ebistree.c b/ebtree/ebistree.c
new file mode 100644
index 0000000..acaf3fa
--- /dev/null
+++ b/ebtree/ebistree.c
@@ -0,0 +1,42 @@
+/*
+ * Elastic Binary Trees - exported functions for Indirect String data nodes.
+ * Version 5.0
+ * (C) 2002-2009 - Willy Tarreau <w@1wt.eu>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+/* Consult ebistree.h for more details about those functions */
+
+#include "ebistree.h"
+
+/* Find the first occurence of a zero-terminated string <x> in the tree <root>.
+ * It's the caller's reponsibility to use this function only on trees which
+ * only contain zero-terminated strings. If none can be found, return NULL.
+ */
+REGPRM2 struct ebpt_node *ebis_lookup(struct eb_root *root, const char *x)
+{
+	return __ebis_lookup(root, x);
+}
+
+/* Insert ebpt_node <new> into subtree starting at node root <root>. Only
+ * new->key needs be set with the zero-terminated string key. The ebpt_node is
+ * returned. If root->b[EB_RGHT]==1, the tree may only contain unique keys. The
+ * caller is responsible for properly terminating the key with a zero.
+ */
+REGPRM2 struct ebpt_node *ebis_insert(struct eb_root *root, struct ebpt_node *new)
+{
+	return __ebis_insert(root, new);
+}