Replace all uses of it by type::field.
Note that since type::field returns a reference to the field, some spots
are used to assign the whole field structure. See ctfread.c, function
attach_fields_to_type, for example. This is the same as was happening
with the macro, so I don't think it's a problem, but if anybody sees a
really nicer way to do this, now could be a good time to implement it.
gdb/ChangeLog:
* gdbtypes.h (TYPE_FIELD): Remove. Replace all uses with
type::field.
