(SIGNATURE_VPTR_NAME): Deleted.  We use the right vptr field in the object now
instead of in the signature pointer/ref.
(build_vptr_ref): Deleted extern declaration.
(tag_identifier, offset_identifier): Added extern decls.
(SIGTABLE_CODE_NAME): Renamed to SIGTABLE_TAG_NAME.
(SIGTABLE_PFN_NAME): Deleted, we'll use VTABLE_PFN_NAME instead.

From-SVN: r10044