* Build with linkage-table by default on x86/NetBSD and
sparc/Linux as well.
* Don't try to be too clever about when to warn user about
alien definitions when saving cores on non-linkage-table
platforms: do it unconditionally.
* Fix parsing of recursive alien record and union types
(reported by Thomas F. Burdick, port of Helmut Eller's
patch for the same problem in CMUCL.)