Locate the Python and faketime binaries
Enable parallel tests.

* find/testsuite/Makefile.am (AUTOMAKE_OPTIONS): Enable
parallel-tests.  This will only include tests known directly via
$(TESTS), not DejaGnu tests.
Check there are no duplicate configuration entries for test files.

* find/testsuite/Makefile.am (EXTRA_DIST_XO): Remove duplicate items.
(EXTRA_DIST_EXP): Likewise.
(checklists): Run with the other checks, using check-local.  Don't
echo the full command, because it will make the summary of the
Automake-driven tests scroll offscreen.
(TEST_EXTENSIONS): Add .sh and .py.
Routinely check .xo and .exp test file lists in a clearer way.

* find/testsuite/checklists.py: Tiny program for checking that the
correct lists of .xo and .exp files exist in the Makefile.am file.
* Makefile.am (checklists): Update target to use the new program.
Make this target phony.