src_distribute.bbclass, src_distribute_local.bbclass: mostly rewritten

src_distribute.bbclass, src_distribute_local.bbclass: mostly rewritten

The code used to reference unavailable variables and mistakenly define
the tasks so fully demonstrating this have not been in use for a
while.

During the code rewrite, it was extended to copy also the patches into
the source distribution directory but using the PF as prefix to avoid
name colision among other recipes.

As 'distsrcall' task was not properly defined and noone noticed it,
until now, it got renamed to 'distribute_sources_all' as it is a
better and more meanful name for the task.

(From OE-Core rev: 6b6e0667871fb5f43b68440954c3ad629dfc92e7)

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>