Add Q_ENUM for QValidator::State

Besides to the usual value for debug output, this is wanted for
some declarative API.

Change-Id: I6c35cad96b6a6f33a7c90e8a254bfe0075e391ee
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

src/gui/util/qvalidator.h

@@ -69,6 +69,7 @@ public:
         Intermediate,
         Acceptable
     };
+    Q_ENUM(State)
 
     void setLocale(const QLocale &locale);
     QLocale locale() const;