QFramePrivate: use direct instead of copy initialization

Probably not performance-relevant here, but easier to read and safer,
too (consider what happens if frect becomes QRectF).

Change-Id: Ia5e4369b550b3a5b899b41ac4cbbda91229f2eb4
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>

src/widgets/widgets/qframe.cpp

@@ -45,7 +45,7 @@
 QT_BEGIN_NAMESPACE
 
 QFramePrivate::QFramePrivate()
-    : frect(QRect(0, 0, 0, 0)),
+    : frect(0, 0, 0, 0),
       frameStyle(QFrame::NoFrame | QFrame::Plain),
       lineWidth(1),
       midLineWidth(0),