storage: switch index data structure from skiplist to std::set

test performance of skiplist and std::set

Change-Id: I0aa7f34e57f17a83b96fed3885d6cc6f59ad52dd
diff --git a/wscript b/wscript
index 537a3e9..02be7f5 100644
--- a/wscript
+++ b/wscript
@@ -68,6 +68,7 @@
 
     # Tests
     bld.recurse('tests')
+    bld.recurse("tests/other")
 
     # Tools
     bld.recurse('tools')