Johnny imported a new emulation framework that solves quite a number
of problems (thanks, Johnny!).

I have a new problem with it:
firefox-bin-java only exists for linux-i386 (because firefox-bin only
exists for it); it depends on sun-jre15, for which both linux-i386 and
linux-x86_64 versions exist. On NetBSD/amd64, the linux-x86_64 version
is built by default. So installing firefox-bin-java pulls in the
x86_64 version of the Java plugin and expects it to work in
firefox-bin.

For binary packages it gets even more interesting -- if you build
sun-jre15, you get the same PKGNAME independent of if you have the
amd64 or i386 version.

We probably want to add a way to differentiate the two. Perhaps
include the EMUL_PLATFORM in the PKGNAME?

Comments?
 Thomas