libiberty: Add support for D `typeof(*null)' types

The D language has a new bottom type `typeof(*null)'.  Null types were
also incorrectly being demangled as `none', this has been fixed to be
`typeof(null)'.

libiberty/ChangeLog:

	* d-demangle.c (dlang_attributes): Handle typeof(*null).
	(dlang_type): Likewise.  Demangle 'n' as typeof(null).
	* testsuite/d-demangle-expected: Update tests.

libiberty/d-demangle.c

@@ -573,9 +573,11 @@ dlang_attributes (string *decl, const char *mangled)
 	case 'g':
 	case 'h':
 	case 'k':
+	case 'n':
 	  /* inout parameter is represented as 'Ng'.
 	     vector parameter is represented as 'Nh'.
-	     return paramenter is represented as 'Nk'.
+	     return parameter is represented as 'Nk'.
+	     typeof(*null) parameter is represented as 'Nn'.
 	     If we see this, then we know we're really in the
 	     parameter list.  Rewind and break.  */
 	  mangled--;
@@ -787,6 +789,12 @@ dlang_type (string *decl, const char *mangled, struct dlang_info *info)
 	  string_append (decl, ")");
 	  return mangled;
 	}
+      else if (*mangled == 'n') /* typeof(*null) */
+	{
+	  mangled++;
+	  string_append (decl, "typeof(*null)");
+	  return mangled;
+	}
       else
 	return NULL;
     case 'A': /* dynamic array (T[]) */
@@ -884,7 +892,7 @@ dlang_type (string *decl, const char *mangled, struct dlang_info *info)
     /* Basic types */
     case 'n':
       mangled++;
-      string_append (decl, "none");
+      string_append (decl, "typeof(null)");
       return mangled;
     case 'v':
       mangled++;

libiberty/testsuite/d-demangle-expected

@@ -83,7 +83,11 @@ demangle.test(ulong)
 #
 --format=dlang
 _D8demangle4testFnZv
-demangle.test(none)
+demangle.test(typeof(null))
+#
+--format=dlang
+_D8demangle4testFNnZv
+demangle.test(typeof(*null))
 #
 --format=dlang
 _D8demangle4testFoZv