bitbake.conf: enable BB_LOCALCOUNT_OVERRIDE by default, please disable if you're...

bitbake.conf: enable BB_LOCALCOUNT_OVERRIDE by default, please disable if you're using AUTOREV

* For now disable autoincrement of revision counter in SRCPV, whoever
  wants it, should enable it in local.conf or distro config.
  (Set it empty BB_LOCALCOUNT_OVERRIDE = "")
* Revision counter is incremented only locally (bad for multiple
  builders filling shared feeds), LOCALCOUNT can be used to maintain
  counter globally in OE metadata (LOCALCOUNT value set in recipe).
* Make sure you disable it, if you want always upgradable paths for git
  recipes without bumping LOCALCOUNT with every SRCREV change
  or if you're using AUTOREV feature.

* LOCALCOUNT == value for revision counter in GIT recipes (NNNN in
  PV="1.0+gitrNNNN+a7401084a72285c8d3485bacf4eed593f303b1b7-r4.4")

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>