adjust to qt_plugin.prf changes, part 1

PLUGIN_TYPE will need to be defined. do this before the respective change
in qtbase, due to the reverse dependency.

Change-Id: I97e7574b48512958689dab0c0697f2edc8666807
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>

src/plugins/accessible/quick/quick.pro

 TARGET  = qtaccessiblequick
 DESTDIR = $$QT.gui.plugins/accessible
 
+PLUGIN_TYPE = accessible
 load(qt_plugin)
+
 include ($$PWD/../shared/qaccessiblebase.pri)
 
 QT += core-private gui-private v8-private qml-private quick-private

src/plugins/qmltooling/qmldbg_ost/qmldbg_ost.pro

 TARGET = qmldbg_ost
 QT       += qml network
 
+PLUGIN_TYPE = qmltooling
 load(qt_plugin)
 
 DESTDIR  = $$QT.qml.plugins/qmltooling

src/plugins/qmltooling/qmldbg_qtquick2/qmldbg_qtquick2.pro

 TARGET = qmldbg_qtquick2
 QT       += qml-private quick-private core-private gui-private v8-private
 
+PLUGIN_TYPE = qmltooling
 load(qt_plugin)
 
 DESTDIR  = $$QT.qml.plugins/qmltooling

src/plugins/qmltooling/qmldbg_tcp/qmldbg_tcp.pro

 TARGET = qmldbg_tcp
 QT       += qml-private network v8-private core-private
 
+PLUGIN_TYPE = qmltooling
 load(qt_plugin)
 
 DESTDIR = $$QT.qml.plugins/qmltooling