[OE-core] Merging AArch64 support

[Marcin Juszkiewicz]

Hello guys

Now, when AArch64 is buildable from public sources it came a time to
work on merging all changes I had to do to get it working with current
OE-Core.

All changes are available in:

git://git.openembedded.org/openembedded-core-contrib hrw/aarch64-support

Those are first versions of patches so if anything has to be changed
feel free to tell. Probably descriptions needs to be updated etc but I
would like to see some kind of review as it was long time since last
time I did OE merging stuff.