[oe] [RFC] Moving PACKAGE_EXTRA_ARCHS to include/tune-*

[Koen Kooi]

Hi,

Currently we set PACKAGE_EXTRA_ARCH in each machine, but nearly all 
entries could get moved to the tune-* files.

So

PACKAGE_EXTRA_ARCHS = "armv4 armv4t armv5te armv6 armv7 armv7a"

Will move from beagleboard.conf to tune-cortexa8.conf but it will use 
'+=' instead of '=' so machines can still do PACKAGE_EXTRA_ARCHS = 
"someleetarch"

Comments, suggestions?

regards,

Koen