these options don't seem particularly useful (they were added in 2001
without any indication of the intended usage). maintaining multiple
static configurations can be best achieved with a script (outside the
build directory, which these options didn't permit to start with).
this obsoletes QTBUG-46690, which refers to these options.
Change-Id: I994c18481cd63d256bb7a6d1948c57f7bd480614
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
6b4496c5f8