Allow linking Boost.Test statically in the test suite
Allow linking Boost.Test statically in the test suite

This is especially useful under Windows where it's built as a static library
by bjam by default.

By default, it is still used dynamically and XMLWRAPP_NO_BOOST_TEST_DYN_LINK
needs to be explicitly predefined when building to avoid it.

vslavik/xmlwrapp,vadz/xmlwrapp,vslavik/xmlwrapp,vadz/xmlwrapp,vslavik/xmlwrapp,vadz/xmlwrapp