tests: Add an enumeration value with DEPRECATED in its name

This should not mean that the enumeration is deprecated.

https://bugzilla.gnome.org/show_bug.cgi?id=730658
scan: Ignore enumeration fields with DEPRECATED in their name

GParamFlags should not be declared deprecated just because it has a
value called G_PARAM_DEPRECATED.

https://bugzilla.gnome.org/show_bug.cgi?id=730658