make's -j option isn't forwarded to ocamlbuild

[adrien-n]

The C stubs currently take quite a bit of time to build and actually dominate the build. Ocamlbuild can also build them in parallel. However "make -jX" will not invoke ocamlbuild with "-j X", preventing the parallel builds.

The simplest way to have parallel builds is to invoke make with the 'OCAMLBUILD="ocamlbuild -j 4"' argument to override the value that has been detected by configure. Obviously this negates the usefulness of the configure check.

I have however no idea on how to implement that in a particularly clean way so maybe adding something in the documentation about the aforementioned argument would be the best solution for the time being.

[axiles]

Now the Makefile passes the variable OCAMLBUILD_FLAGS to ocamlbuild

It possible to have the parallel build by either specifying the variable at configuration time:

./configure  OCAMLBUILD_FLAGS="-j 4"
make

or you can also overrided it during the build

OCAMLBUILD_FLAGS="-j 4" make

Information about OCAMLBUILD_FLAGS can be obtained by entering:

./configure --help