gdb: remove TYPE_CHAIN

IMO, there is no point in keeping this macro.  Remove it and access the
field directly.  If we ever want some kind of abstraction in front of
the field, then we'll add a method.

Change-Id: Ia45cc7be5c6d9d09a9d4903f01b1ab282839a9c2
Approved-By: Andrew Burgess <aburgess@redhat.com>
3 files changed