Deprecate ErrorDomain

The previous ErrorDomain blob was never actually scanned or used, and
it was kind of a lame API conceptually.

To keep some compatibility, rather than removing the enumeration
values, rename them to _INVALID, and don't bump the typelib version.
This should in theory allow a new libgirepository to read an old
typelib.

Based on a patch from Colin Walters

https://bugzilla.gnome.org/show_bug.cgi?id=602516