QEvent: mark registerEventType() as no-throw

The new implementation using an atomic bit field performs no
memory allocations and thus cannot throw anymore.

Change-Id: If6a98f307ab4e6a7c3fe3c54763ac0c6d2da4ac0
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/kernel/qcoreevent.cpp

@@ -471,7 +471,7 @@ static inline int registerEventTypeZeroBased(int id) Q_DECL_NOTHROW
     Returns -1 if all available values are already taken or the
     program is shutting down.
 */
-int QEvent::registerEventType(int hint)
+int QEvent::registerEventType(int hint) Q_DECL_NOTHROW
 {
     const int result = registerEventTypeZeroBased(QEvent::MaxUser - hint);
     return result < 0 ? -1 : QEvent::MaxUser - result ;

src/corelib/kernel/qcoreevent.h

@@ -302,7 +302,7 @@ public:
     inline void accept() { m_accept = true; }
     inline void ignore() { m_accept = false; }
 
-    static int registerEventType(int hint = -1);
+    static int registerEventType(int hint = -1) Q_DECL_NOTHROW;
 
 protected:
     QEventPrivate *d;