bug#50118: Racket: `raco exe` can't find Racket executable for variant cs

[Philip McGrath]

This was fixed in Guix commit fd22921490f40044d58be8ddc3b38b8be12188a6 
(September 10, 2021). See: 
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=50419

-Philip