Add camlp4 formula and hook it into OCaml/OPAM package

See #33596 for related discussion.
woops, gone in 45b70a873a2e6c8c031e4b1d0d7808fa0e1e59b8

> On 27 Oct 2014, at 19:50, Misty De Meo <notifications@github.com> wrote:
> 
> In Library/Formula/objective-caml.rb:
> 
> > @@ -22,7 +24,17 @@ def install
> >                            "-cc", ENV.cc,
> >                            "-with-debug-runtime",
> >                            "-aspp", "#{ENV.cc} -c"
> > +    args = %W[
> 
> Remove the first run of configure?
> 
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