External Core: print function types correctly, improve newtype pretty-printing

- In a previous patch I broke the printing of fully-applied arrow
types (e.g., "a -> b" was "(ghczmprim:GHCziPrim a b)") by z-encoding
package names and not updating the primitive module name as defined in
External Core accordingly. Fixed. (Mega sigh...)

- Make newtype decls print slightly more readably.

compiler/coreSyn/ExternalCore.lhs

@@ -86,7 +86,7 @@ type Id = String
 primMname :: Mname
 -- For truly horrible reasons, this must be z-encoded.
 -- With any hope, the z-encoding will die soon.
-primMname = "ghc-prim:GHCziPrim"
+primMname = "ghczmprim:GHCziPrim"
 
 tcArrow :: Qual Tcon
 tcArrow = (primMname, "(->)")

compiler/coreSyn/PprExternalCore.lhs

@@ -61,7 +61,7 @@ ptdef (Newtype tcon tbinds (coercion,k) rep) =
 -- At the same time, we need the newtype decl to declare the tycon itself.
 -- Sigh.
   text "%newtype" <+> pqname tcon <+> (hsep (map ptbind tbinds)) 
-    <+> axiomclause <+> repclause
+    $$ indent (axiomclause $$ repclause)
        where  axiomclause = char '^' <+> parens (pqname coercion <+> text "::"
                                      <+> pkind k)
               repclause   = case rep of