Using the standard inspect module instead of accessing __doc__ directly allows
the tests to pass both when using and not using -builtin, as whitespace-only
differences between the docstrings don't matter then because inspect.getdoc()
removes the indentation and the leading and trailing spaces.
This is similar to what had been already done for python_docstring unit test
in fa282b3540.
This is unnecessary and inconsistent with "builtin" case in which the
docstrings are not indented in the generated C++ code, thus making it
impossible to write tests working in both cases.
Most of the changes in this commit simply remove the extra whitespace from the
expected values in the tests.
Update Doxygen-specific Python unit tests to work with the new indentation.
Update one of Doxygen-specific Java tests to still build with the new handling
of srcdir.
William S Fulton