Enable automake parallel-tests for make check.

Enable automake parallel-tests for make check.

The parallel-tests option was introduced in automake 1.11 and is the
default since automake 1.13. All tests can now be ran in parallel with
make check -j. To enable this all tests are ran in their own temporary
directory so they don't stomp on each others input or output files.
On my machine (4 cores) make check takes ~20 seconds, but now with
make check -j8 takes only ~4 seconds.

ChangeLog:

       * configure.ac (AM_INIT_AUTOMAKE): Request parallel-tests.

tests/ChangeLog:

       * Makefile.am (installed_TESTS_ENVIRONMENT): Export environment,
       remove wrapper.
       (TESTS_ENVIRONMENT): Likewise.
       (installed_LOG_COMPILER): New variable defining wrapper.
       (LOG_COMPILER): Likewise.
       * run-*.sh: Fixup location of input and output files.
       * test-subr.sh: Create test_dir, pushd to execute test in.
       (trap): Remove test_dir.
       (testfiles): Use abs_srcdir.
       (installed_testrun): Match on abs_builddir or abs_top_builddir.
       (self_test_files): Adjust path.

Signed-off-by: Mark Wielaard <mjw@redhat.com>