Allow installation of extracted packages with pkg.m

[David Bateman]

Thomas Weber wrote:
>> I don't know pkg.m very well, so it would help me if someone who does
>> could comment on this patch.  If the above is generally OK and the
>> loop is not needed, then please resubmit the patch with the loop
>> removed.  Also please explain the apparently stray "endif".
> 
> Well, I asked about the loop, so someone else should comment. The
> "endif" is explained above.

The loop here is a holdover from when I thought we might be able to
install all of octave-forge with a single pkg install command. The
octave-forge bundle is just a tarball of the individual packages and so
it should be possible to install them all in one go.

However, that doesn't really make sense as there are packages in
octave-forge that should only be installed on some platforms.. The loop
should go..

D.