use qt_tool.prf for dumpdoc

it was previously skipped - probably because it contains QT+=widgets.
it's still a command line tool, though.

Change-Id: I1c641d80d1d2ccdf25ffa4613ad5030c9695a8a4
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

tools/dumpdoc/dumpdoc.pro

-TEMPLATE = app
-
-CONFIG  += console
 QT += axcontainer widgets
 
 SOURCES += main.cpp
 
-target.path = $$[QT_INSTALL_BINS]
-INSTALLS += target
-
+load(qt_tool)