tests: minor optimizations/simplifications in some aclocal tests * acloca11.test: Instead of running ./configure and then grepping the file it has produced, directly grep configure. Add trailing `:' command. * acloca12.test: Likewise. * acloca10.test: Likewise. Also, remove the autom4te caches by hand, instead of sleeping to ensure they get outdated and ignored. * aclocal9.test: Likewise. * acloca18.test: Likewise. Also, do not remove file `foo', which is not being created anymore. * acloca20.test: The test makes sense only if the system support real symlinks, so skip it if this is not the case. This allows for various simplifications.