buttontester.pro has to be renamed to mousebuttons.pro because it lives
in mousebuttons subdirectory, to which examples/widgets/widgets.pro is
pointing by SUBDIRS variable.
Change-Id: I04bbd85713321337fbe8cbccfa6284f12b677279
Reviewed-by: Rick Stockton <rickstockton@reno-computerhelp.com>
Reviewed-by: Casper van Donderen <casper.vandonderen@nokia.com>
