re: introduce OBJMACHINE_ARCH

[matthew green <mrg%eterna.com.au@localhost>]

i'm still not a fan.  i am positive you can do this with
MAKEOBJPREFIX.

it also relies upon a new feature to work, where as using
the existing methods works going back to some distant time
in the past.  it's frustrating when the build environment
changes so heavily between releases and i'm yet to see why
MAKEOBJPREFIX isn't useable here.

here, this seems to work:

MAKEOBJPREFIX='${NETBSDSRCDIR}/obj.${MACHINE}-${MACHINE_ARCH}/${.CURDIR:S/${NETBSDSRCDIR}\///}'

enjoy!


.mrg.