Bug 11188 - Make gather_print_notices.pl die on failed open()

Bug 11188 - Make gather_print_notices.pl die on failed open()

Problem:
If you tell gather_print_notices.pl to write output to a location
you do not have write access to, it will silently fail to write the
data, but still mark unsent messages as sent.

Solution:
This patch adds two lines of defense:
1. Check that the location given for the output is writable
2. use "open() or die" instead of just "open()" when writing the
   output
The first measure should catch most of the potential errors, but
I guess a directory can be writable, but the open() still can fail
because the disk is full or something similar.

To test:
- Make sure you have some unsent messages in the message_queue table,
  that do not have an email adress
- Apply the patch
- Run the script, pointing at a location you do not have access to
  write to. Check that the script exits with an appropriate error
  message, and that the unsent messages are still unsent. Do this
  both with and without the -s option.
- To fake passing the first line of defence, comment out line 62
  and put this in instead:
  if ( !$output_directory || !-d $output_directory ) {
- Run the script again as above, check you get an appropriate
  error and that the message queue is not touched
- Reset line 62 to how it was
- Run the script against a directory you do have access to write to
  and check that output is produced as expected and that messages
  are marked as sent
- Sign off

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Passes all tests and QA script.
Works as described.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit e8a24c35f64cb461a80f768b505bbf16c49dfeff)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>