Also now permit interactivly running tests without explicitly setting
$srcdir. This now works if we are inside ./tests and fails, as before,
when we are in a different directory.
Detected by shellcheck via CodeFactor.io
This is required to support parallel test runs.
Among others, make thise files dynamic:
* test-spool
* rsyslog.input
* rsyslog.out*.log
* tmp.in
Also:
* convert presort test statement to function
* cleanup imfile truncation test
* cleanup imfile-growing-file-id test
some cruft was left due to copy and paste error
* serialize mysql tests
Support tools (like tcpflood) are also upgraded to support the
necessary dynamic port.s
This is part of the effort to make parallel testing possible.
We move parts of the cleanup to the buildbot cleanup, as we cannot
clean out instances on each test when we run parallel tests.
