Fix disableBlurBehindWindow(QWidget*)

The functions to handle blur-behind on QWidgets are inline wrappers that
call the functions taking QWindow. disableBlurBehindWindow(QWidget*)
was calling the *enable* function for QWindow* instead of the disable
function. In other words, disableBlurBehindWindow was enabling blur-behind
instead of disabling it.

Change-Id: I02cc4b0ad956afe2d81fc5f7783986b799bd9cd2
Reviewed-by: Jake Petroules <jake.petroules@petroules.com>
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Bump MODULE_VERSION to 5.2.1

Change-Id: I132c72934727f344f850d117a7663fcff9e0ec5e
Reviewed-by: Matti Paaso <matti.paaso@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Merge remote-tracking branch 'origin/release' into stable

Change-Id: Id23fc1705d026f3da5eb1a5f13f3e9aca368c7ed
Merge remote-tracking branch 'origin/stable' into dev

Conflicts:
	.qmake.conf

Change-Id: Icf864310f47d54237a10d7a10fa85c14ac313a7e