qsslsocket_schannel: update QMutexLocker usage

Following 77d812683f QMutexLocker is now a
templated class which should in most cases be deduced automatically.
Doesn't work here because of the global static wrapper.

Change-Id: I62fda0651eac12f3234396cb7e41a26df8cc8b46
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

src/network/ssl/qsslsocket_schannel.cpp

@@ -515,7 +515,7 @@ Q_GLOBAL_STATIC(QRecursiveMutex, qt_schannel_mutex)
 
 void QSslSocketPrivate::ensureInitialized()
 {
-    const QMutexLocker locker(qt_schannel_mutex);
+    const QMutexLocker<QRecursiveMutex> locker(qt_schannel_mutex);
     if (s_loadedCiphersAndCerts)
         return;
     s_loadedCiphersAndCerts = true;