Oversight on armv7 bulk commit: Make MACHINE_ARCH be armv7 for new
enough processors. This isn't ideal, because one could still compile
MACHINE_ARCH armv6, but with armv7 options enabled. We don't normally
do that, and it's a bit of an edge case so accept the less than ideal
solution here in the absence of something better.

Reported by: strejda@
Sponsored by: Netflix