[gfortran,patch] Fix PACK, SPREAD and CSHIFT for zero-sized arrays

[François-Xavier Coudert]

I'm answering to a very patch review from Steven Bosscher:
http://gcc.gnu.org/ml/gcc-patches/2006-07/msg01239.html

> This whole hunk could be implemented as the easier-to-understand:

I don't think it works as well, because if arraysize <= 0 you really
need the return statement and not to go on with the rest of the
function. So, I intend to commit the original version this week-end
unless there's an objection.

FX