add missing dependency check to widgets plugin

QtQuick widgets plugin depends on both QtWidgets and QtQuick module, if
do not check 'quick', there will be an error: "Project ERROR: Unknown
module(s) in QT: quick" when running make if failed to check for QtQuick
module due to no opengl/es1/es2 found during config test.

Change-Id: I39d78b9cd9aa9c7f0acf79fdcfc06749ffc10e31
Reviewed-by: Liang Qi <liang.qi@digia.com>