Per-arch CFLAGS

[Simon J. Gerraty]

On Sat, 15 Mar 2014 08:28:15 -0600, Ian Lepore writes:
>After consulting with Warner a bit I came up with the attached rather
>simple change that does the job perfectly.  It adds support for a
>CFLAGS.arch variable that can be set in make.conf or the command line or
>environment.  Any objections to this?

No, looks fine.
FWIW we do much the same in the Junos build, but ${MACHINE} rather
than ${MACHINE_ARCH} both have their uses in fact.
Esp since we use the pseudo machine "host" to represent the build host
(for host tools etc).