has a special hack to find all the files in instdir so ideally it should
not be necessary to put these directories on the include path.
Clean up readlicense_oo to make that possible; also copying license.txt
as-is to LICENSE on Unix but first converting it on WNT is rather silly...
Tested-by: LibreOffice gerrit bot <firstname.lastname@example.org>
Reviewed-by: Michael Stahl <email@example.com>