Further extended Makefile.global/build/configure so that we can
have a 'template' file for each OS (and each version of OS, as in BSDi)
which is used as much as possible to generate Makefile.global
Any future ports should look at using the template file as a basis,
before moving over to Makefile.global.
This will most probably break alot of the ports, atho I've tried to
be very neat about it...