tests: avoid running into timing issues due to sanity change.

tests: avoid running into timing issues due to sanity change.

* tests/acloca10.test, tests/acloca18.test, tests/aclocal9.test:
Insert strategic sleep before aclocal reruns, to ensure files
are newer.
* tests/python11.test: Use --force for repeated autotools runs.
Reports from the NixOS Hydra build daemon via Ludovic Courtès.

Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>