testsuite: do not fail on systems without read permissions.

testsuite: do not fail on systems without read permissions.

* tests/instfail-info.test: Do not use the `non-root'
requirement for testing whether files may be made unreadable;
instead use `test -r' and skip the test if that still works.
* tests/instfail-java.test: Likewise.
* tests/instfail-libtool.test: Likewise.
* tests/instfail.test: Likewise.
* tests/instmany-mans.test: Likewise.
* tests/instmany-python.test: Likewise.
* tests/instmany.test: Likewise.
* tests/parallel-tests9.test: Likewise.

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