ext/pb_ds/regression/trie_no_data_map_rand

[Benjamin Kosnik]

> > I was trying to track down what PRE is doing to these testcases
> > that causes them to crash, and I noticed that while I can't get
> > them to crash without turning on PRE (IE -fno-tree-pre "fixes"
> > them), they seem to have a *massive* number of valgrind failures
> > consisting of "invalid reads" even with PRE turned off.

I'll look at this today.

-benjamin