[CM] unbound variable with CM_Patterns.scm

[bil at ccrma.Stanford.EDU]

In r7rs.scm, change line 433 from (define-expansion ...)
to (define-macro ...) -- not sure why this fixes it!

(define-expansion (define-record-type type make ? . fields)

to

(define-macro (define-record-type type make ? . fields)