Restore short type names for int and real in the Coq driver.

drivers/coq-common.gen

@@ -23,6 +23,8 @@ theory BuiltIn
 
   prelude "Require Import BuiltIn."
 
+  syntax type int "Z"
+  syntax type real "R"
   syntax predicate  (=)   "(%1 = %2)"
 end