[oe] [RFC] Partial merge of SRCPV

[Martin Jansa]

Please consider applying this patch series.

Proposed and discussed in [1], the main reason for NACK (multiple builders
uploading to shared feeds) was resolved with bitbake patch [2] and it's 
enabled by default in PATCH 1/6. It needs bitbake 1.10 or master, but Koen
confirmed yesterday that he is using 1.10 already.

People not using multiple builders or any of changed recipes don't need to 
upgrade their bitbake, just keep your tmp/cache dir even for rebuilds from
scratch (as you already should, if you have ever used AUTOREV).

I'll keep SRCPV changes for other recipes in shr/unstable branch so maintainers
of other recipes can move to SRCPV easily too.

WARNING: don't use BB_LOCALCOUNT_OVERRIDE with AUTOREV, it will make revision
counter in PV constant and chaning SRCREV is not enough to ensure increasing PV.

[1] : http://www.mail-archive.com/openembedded-devel@lists.openembedded.org/msg01325.html
[2] : http://git.openembedded.org/cgit.cgi/bitbake/commit/?h=1.10&id=2f32735463159e9e42e03819d6b505dba49c7f17