Utils: Fix compile warning

unused variable

Change-Id: I84523cf221029d3a43b698f941e230441338d916
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/libs/utils/mimetypes2/mimedatabase.cpp

@@ -78,12 +78,14 @@ MimeDatabasePrivate::~MimeDatabasePrivate()
 {
 }
 
+#if 0
 #if 0 //def QT_BUILD_INTERNAL
 Q_CORE_EXPORT
 #else
 static const
 #endif
 int mime_secondsBetweenChecks = 5;
+#endif
 
 bool MimeDatabasePrivate::shouldCheck()
 {