base.bbclass: drop compatibility moving of sources into workdir

base.bbclass: drop compatibility moving of sources into workdir

Potentially there could be a grace period for fixing recipes (with warnings, etc),
on the other hand, changes to git unpacking destination would already
break various layers, so we might as well make this a hard qa error and drop
the magic at the same time.

I commit to sending fixes for layers included in autobuilder testing
(meta-oe/arm/intel/virt/agl/aws/mingw/etc).

SOURCE_BASEDIR is at the same time adjusted to be calculated relative
to UNPACKDIR (previously it only worked if S was set to
WORKDIR/something/otherthing, and that is no longer working). It is also
no longer removed from the filesystem, as content of unpackdir is managed elsewhere.

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>