* guix/records.scm (print-record-abi-mismatch-error): New procedure.
<top level>: Add 'set-exception-printer!' call.
(current-abi-identifier, abi-check): New procedures.
(make-syntactic-constructor): Add #:abi-cookie parameter. Insert calls
to 'abi-check'.
(define-record-type*)[compute-abi-cookie]: New procedure.
Use it and emit a definition of the 'current-abi-identifier' for TYPE.
* tests/records.scm ("ABI checks"): New test.