MSVC2015: Compile fix

Q_DECL_NOTHROW needs to be present at the definition as well in VS2015.

Change-Id: I8a6def607aa4ae9c9fe64386a38fc1c728edd8d1
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Reviewed-by: Oliver Wolff <oliver.wolff@theqtcompany.com>

src/network/ssl/qsslellipticcurve_dummy.cpp

@@ -57,7 +57,7 @@ QSslEllipticCurve QSslEllipticCurve::fromLongName(const QString &name)
     return QSslEllipticCurve();
 }
 
-bool QSslEllipticCurve::isTlsNamedCurve() const
+bool QSslEllipticCurve::isTlsNamedCurve() const Q_DECL_NOTHROW
 {
     return false;
 }