cmd/compile/internal/gc: introduce type for decl contexts/storage classes

Change-Id: I956e27fa07f16060b8f41b986d991c36557f7c12
Reviewed-on: https://go-review.googlesource.com/16332
Reviewed-by: Keith Randall <khr@golang.org>
diff --git a/src/cmd/compile/internal/gc/walk.go b/src/cmd/compile/internal/gc/walk.go
index 43398a3..875b7ab 100644
--- a/src/cmd/compile/internal/gc/walk.go
+++ b/src/cmd/compile/internal/gc/walk.go
@@ -288,7 +288,7 @@
 			// so that reorder3 can fix up conflicts
 			var rl *NodeList
 
-			var cl uint8
+			var cl Class
 			for ll := Curfn.Func.Dcl; ll != nil; ll = ll.Next {
 				cl = ll.N.Class &^ PHEAP
 				if cl == PAUTO {