ocaml: hash table collisions CPU usage DoS (oCERT-2011-003)

OCaml 3.12.1 and earlier computes hash values without restricting the ability to trigger hash collisions predictably, which allows context-dependent attackers to cause a denial of service (CPU consumption) via crafted input to an application that maintains a hash table.

caml-light <= 0.75 uses mktemp() insecurely, and also does unsafe things in /tmp during make install.