6g cleanup suggested by ken.
remove TPTR wrapper around TMAP, TCHAN, TSTRING.

R=ken
OCL=22406
CL=22409
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index da4f871..a46e76a 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -626,6 +626,7 @@
 Type*	aindex(Node*, Type*);
 int	isnil(Node*);
 int	isptrto(Type*, int);
+int	istype(Type*, int);
 int	isptrsarray(Type*);
 int	isptrdarray(Type*);
 int	issarray(Type*);