To formalize they are now XML-compliant (with some asterisks.)
Also to help syntax highlighters work on them to make their content more
readable.
Also:
- Delete empty comment decorations.
- GHA/checksrc: simplify XML check.
- runtests: fail to load test data with XML prolog missing.
Follow-up to bfe6eb1c06#19927
Follow-up to 87ba80a6dfCloses#19946
There are 58 non-compliant files. Mark them with the `notxml` keyword.
Also include the compliant ones in the GHA/checksrc xmllint CI job.
Also:
- delete XML prolog from the 3 test data files that had them.
- FILEFORMAT.md: document the `notxml` keyword.
- FILEFORMAT.md: fix a typo.
Follow-up to de49cc89ab#19470
Follow-up to f3095f0dbd#19528
Follow-up to 87ba80a6dfCloses#19595
To ensure Perl invocations within tests call the same Perl binary used
for running the tests, as specified or auto-detected via `PERL` env
(autotools) or `PERL_EXECUTABLE` setting (cmake). Instead of the first
`perl` executable found in `PATH`.)
Cherry-picked from #14949Closes#15097
Also introduce 'notexists' for verifying that directory entries do not
exist after a test. Now an explicit supported feature instead of using
"funny" perl in postcheck.
Closes#15046
Python precheck/postcheck alternatives were included but commented out.
Since these are not used and perl is guaranteed to be available to run
the perl versions anyway, the Python ones are removed.
