MPR#6053: less verbose flags for ocamlbuild

[damiendoligez]

PR transferred from https://caml.inria.fr/mantis/view.php?id=6053
[original reporter: @avsm ]

We're using ocamlbuild and ocamlfind for all of our examples in Real World OCaml, and it's painfully verbose to use:

$ ocamlbuild -use-classic-display -use-ocamlfind -tag thread -pkg core foo.native

...for every single build command. It would be wonderful if a couple of the more frequently used flags could provide shorter alternatives. My ideal command line above would be:

$ ocamlbuild -vf -tag thread -pkg core foo.native

(i.e. map -use-classic-display to -v and -use-ocamlfind to -f, since neither of those can be shortened via alternative mechanisms such as a _tags file)

[dbuenzli]

Related to #48

[whitequark]

Isn't this what corebuild does now?

[whitequark]

Also, I like the idea of having the -v and -f flags.