tests: better name for a couple of tests Two tests checking "make -n" behaviour with the parallel-tests harness has been introduced in the Automake repository in the past: one of them ('parallel-tests-dryrun.test') in the maint branch, the other one ('parallel-tests-dry-run.test') in the master branch. Needless to say, their too-much-similar names can be a great source of confusion now. Moreover, the two tests have been written during distinct refactorings, and are meant to exercise different code paths and/or usage scenarios, so that no one of them subsumes the other, and they should be both kept. Thus we simply rename both of them to avoid future confusion. * tests/parallel-tests-dryrun.test: Renamed ... * tests/parallel-tests-dry-run-1.test: .. to this. * tests/parallel-tests-dry-run.test: Renamed ... * tests/parallel-tests-dry-run-2.test: .. to this. Add cross-reference among them. * tests/list-of-tests.mk: Adjust.