Wrong -outputdir passed for qdoc when generating ActiveQt docs on Windows

When generating doc-related makefiles on Windows, for ActiveQt qdoc is run with -outputdir pointing to qtactiveqt/doc/qtaxbase, when the correct one would be qtactiveqt/doc/activeqt. QDoc cannot locate the activeqt.index file when linking from other docs (notably, qtdoc), as it assumes the index file (base)name to be the same as the module (folder) name.

This works on all other platforms except Windows, presumably because the qt_module is not being loaded.