Un-bootstrapping of ocamlbuild, clean-up phase:
- removed boot/myocamlbuild.boot, _tags, myocamlbuild.ml, etc
- removed shell scripts in build/, now unused
- revised configuration and build of tools/ocamlmklib.


git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@14353 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02