Replace ocamlc tests with ocamlopt tests since they're less noisy.

There's a bug with ocamlc that uses "char*" instead of "const char*" for
global string variables. This causes g++ to be very noisy when linking
ocamlc programs. That's why the ocaml test used to cat to /dev/null.
ocamlopt doesn't have this problem, so we can get rid of the >/dev/null,
which may obscure some problems.

llvm-svn: 80968