Change template parameter name of qt_check_for_QOBJECT_macro

'T' is a fairly common name for template parameter. So if we use it in
Q_OBJECT, it means you cannot use it as a template parameter name of the
object itself (otherwise it does not compile as it shadow a template
parameter)

Use a more explicit name instead

Change-Id: Id317c5b11d87f370eed6d1dc0b0142c9eb4994db
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>