Autotest: loops of tests

[Ralf Wildenhues]

In order to test several compilation variants on the same small set of
files and to reduce bugreport turnaround time, it would be helpful
if, after the first failure, the other tests would still be run.
OTOH, I would not like to repeatedly mention the files as AT_DATA input.

Essentially, something like this:

for flag in -foo -bar
do
  AT_SETUP(test with flag $flag.)

  AT_DATA(file.cc, ...)
  AT_CHECK($compile $flag ..)
  AT_CLEANUP
done

except that AT_SETUP does not to work inside a shell compound command.

Alternatively, I would be happy as well with any other means which
achieves almost the same effect.  Like:
- have a macro like AT_CHECK which does not stop upon failure but allows
  me to record failure so I can skip to the next set of AT_CHECKs.
- have a macro to output status messages in-between so I know which
  test will be next, and can output failure.

Thanks, and sorry again for not posting patches,
Ralf