${MACHINE_ARCH}--freebsd${OSREL} is now passed to CONFIGURE_ARGS if
GNU_CONFIGURE is defined. Take the target out of CONFIGURE_ARGS of
some ports that added it explicitly; define it as
${MACHINE_ARCH}--freebsd if the port doesn't like the ${OSREL} part;
define it as something else (such as ${MACHINE_ARCH}--freebsdelf if
the port requires that; define it as an empty string if the port
doesn't like it at all.
The last might be a sign that a GNU_CONFIGURE port actually doesn't
use GNU's version of configure at all; but I don't have time to go
look at them all, we'll fix them as time goes on.
At least we've got much fewer "-unknown-"s in the tree as the result. :)
