General way of passing make options?

[Denis Bueno]

Hi all,

I'm curious if there is a general way to pass options to the underlying
make(1) (assuming the build phase actually uses make) call?  I ask because I
use an Intel Core 2 Duo, and if the Makefile allows it, I'd like to pass
-j<n> to make when I build.  (I realise not every Makefile behaves properly
with this option, but I'm willing to live with fiddling with that.)

Adding a variant like:
    variant fast_build {
        build.target -j2 all
    }
To the build seems to work, but I'm not sure that's The Right Solution.

Any suggestions?

Thank you.

-Denis