Make sure directory is created for trie data

trie.c

@@ -5,6 +5,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <sys/stat.h>
 
 struct edge {
 	char* label;
@@ -275,6 +276,7 @@ bool ffdb_trie_set( const char* filename, const char* key, const char* value )
 	char* key_escaped = escape(key);
 	bool result = false;
 
+	mkdir( filename, 0755 );
 	root = load_root_node(filename);
 
 	if( !trie_entry_set( root, key_escaped, value ) ) {