move things out of sys into os and runtime

R=r
OCL=28569
CL=28573
diff --git a/test/typeswitch.go b/test/typeswitch.go
index 5ad694d..0a421ae 100644
--- a/test/typeswitch.go
+++ b/test/typeswitch.go
@@ -6,6 +6,8 @@
 
 package main
 
+import "os"
+
 const (
 	Bool = iota;
 	Int;
@@ -31,7 +33,7 @@
 func assert(b bool, s string) {
 	if !b {
 		println(s);
-		sys.Exit(1);
+		os.Exit(1);
 	}
 }