Don't allow make to become shadowed

Deals with old installations of mingw64, in particular on GitHub
Actions.

src/state/opamEnv.ml

@@ -307,7 +307,7 @@ let rezip_to_string ?insert z =
   join_var (rezip ?insert z)
 
 let cygwin_non_shadowed_programs =
-  ["bash.exe"; "sort.exe"; "tar.exe"]
+  ["bash.exe"; "sort.exe"; "tar.exe"; "make.exe"]
 
 let apply_op_zip ~sepfmt var op arg (rl1,l2 as zip) =
   let arg = transform_format ~sepfmt var arg in