Remove obsolete scatter output hook

There are no users of it in main tree and recent merge
of multiple outputs branch makes it obsolete for private trees
too.

At the time hook was created, recently merged multiple output
branch was relying on passing flags to autotools to split
outputs, which obviously wasn't working for other build systems

Scatter output was taking different approach where files were
moved out from a build tree based on known  paths, which is more
or less what current multiple-outputs.sh hook is able to do too.