Coq: ignore the "type unit = ()" declaration in why3.Unit

drivers/coq-common.gen

@@ -24,6 +24,11 @@ theory BuiltIn
   syntax predicate  (=)   "(%1 = %2)"
 end
 
+
+theory Unit
+  syntax type unit "unit"
+end
+
 theory Bool
 
   syntax type bool   "bool"

drivers/coq-ssreflect.drv

@@ -34,6 +34,10 @@ Unset Printing Implicit Defensive.
 
 end
 
+theory Unit
+  syntax type unit "unit"
+end
+
 theory HighOrd
   syntax type (->) "(%1 -> %2)"
   syntax function (@)  "(%1 %2)"