...otherwise PresetHandler::getOrCreateRootStorageShare
(framework/source/accelerators/presethandler.cxx) will cause a
com.sun.star.io.IOException: "URL
"file:///.../solver/unxlngx6/unittest/user/config/soffice.cfg" passed to
css.embed.FileSystemStorageFactory.createInstanceWithArguments does not denote
an existing directory" in some CppunitTests.  (And
1eecb8df "Some cleanup and consolidation of the
Impress layout work" removed the last file that got definitely created in that
directory from test/Package_unittest.mk.)

Change-Id: Idbe42fdd6b06194781cceef62c50531ce0e1c706