[REG] qsslkey autotest has compile error when QT_NO_SSL is defined

If QT_NO_SSL is defined, qtbase/tests/auto/network/ssl/qsslkey/tst_qsslkey.cpp fails to compile with the following error:

tst_qsslkey.cpp:129:53: error: incomplete type 'QSslConfiguration' used in nested name specifier
     const auto supportedCurves = QSslConfiguration::supportedEllipticCurves();
                                                     ^~~~~~~~~~~~~~~~~~~~~~~

This occurs because the definition of the QSslConfiguration class is protected by "#ifndef QT_NO_SSL".

The code that fails to compile was introduced recently in the commit 4f658d04da for QTBUG-46203.