bug#70934: Document how to debug failing tests

[Bruno Haible]

Hi,

While running the libtool test suite in a continuous integration environment,
I saw two test failures. In order to investigate these test failure, I had
to understand how to pass additional options, and which options, to the
testsuite "program". I did not find this information in the HACKING file.
Therefore here is a patch to add it to the HACKING file.

0001-Document-how-to-debug-failing-tests.patch
Description: Text Data