[commit] copyright-header updates...

[Joel Brobecker <brobecker at adacore dot com>]

Hello,

Here is a short series of patches that I just applied to our CVS.
The initial idea was to update copyright.py to tell the user to
update gdb.texinfo and refcard.tex by hand, because these files
contain multiple instances of a copyright header. This is actually
patch #1.

But upon testing, I found a few other things:
  - We need to update the path to gnulib in copyright.py, due to
    the change of location for our gnulib import;
  - Minor deviation in copyright year syntax, or missing copyright
    headers...
The other patches address all these issues...

Checked in.