Remove the use of QMutexPool from QtDBus loading of libdbus-1

Change-Id: Ifea6e497f11a461db432ffff1449b013c2302d38
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

src/dbus/qdbus_symbols.cpp

@@ -36,7 +36,6 @@
 #include <QtCore/qlibrary.h>
 #endif
 #include <QtCore/qmutex.h>
-#include <private/qmutexpool_p.h>
 
 #ifndef QT_NO_DBUS
 
@@ -74,8 +73,10 @@ bool qdbus_loadLibDBus()
 
     static bool triedToLoadLibrary = false;
 #ifndef QT_NO_THREAD
-    QMutexLocker locker(QMutexPool::globalInstanceGet((void *)&qdbus_resolve_me));
+    static QBasicMutex mutex;
+    QMutexLocker locker(&mutex);
 #endif
+
     QLibrary *&lib = qdbus_libdbus;
     if (triedToLoadLibrary)
         return lib && lib->isLoaded();