Replace DEF!METHOD and SB!XC:DEFMETHOD with just DEFMETHOD.
PRINT-OBJECT works in cold load for methods which don't need
fancy method combination. As just one nifty example:
% src/runtime/sbcl --core output/cold-sbcl.core
* (sb-thread:list-all-threads)
(#<SB-THREAD:THREAD "main thread" RUNNING {
1002BE8F83}>)
instead of infinitely looping due to thread<->mutex pointers.
For complicated methods, there's DEF*METHOD which is what
DEF!METHOD was. The old name was bad; unlike other DEF!thing
macros, it had (and has) no effect upon the host Lisp.
Also we can reduce the incredible number of hacks that were
necessary to get MAKE-LOAD-FORM working without methods.