make match exception transparent

This push makes the exn:misc:match exception transparent. This
matches other racket-raised user exceptions.

The motivation for this change was breakage in the handin-server;
specifically, the discussion in

https://groups.google.com/forum/#!topic/racket-users/nEos3-osoWE

...in which the handin-server was not behaving the same on exn:misc:match
because it was not transparent. This caused the handin server to
refuse to rewrite these exceptions, resulting in less helpful
messages for users.

racket/collects/racket/match/runtime.rkt

@@ -17,7 +17,8 @@
 (define match-equality-test (make-parameter equal?))
 
 (define-struct (exn:misc:match exn:fail) (value srclocs)
- #:property prop:exn:srclocs (lambda (ex) (exn:misc:match-srclocs ex)))
+  #:property prop:exn:srclocs (lambda (ex) (exn:misc:match-srclocs ex))
+  #:transparent)
 
 
 (define (match:error val srclocs form-name)