QCommandLineOption: never inline the warning function

We suppose that this function will never be called, yet the
compiler still inlines it in all four places.

Stop it.

Change-Id: If601bc3644cacb77aeab9d615578e4afb349a73e
Reviewed-by: David Faure <david.faure@kdab.com>

src/corelib/tools/qcommandlineoption.cpp

@@ -265,6 +265,8 @@ namespace {
 
             return false;
         }
+
+        Q_NEVER_INLINE
         static bool warn(const char *what) Q_DECL_NOEXCEPT
         {
             qWarning("QCommandLineOption: Option names cannot %s", what);