maps have == so maps should work as map keys.
fix tests of bad map keys to use slices instead.

R=r
DELTA=7  (0 added, 1 deleted, 6 changed)
OCL=31123
CL=31145
diff --git a/test/cmp5.go b/test/cmp5.go
index 7500974..2a55f7b 100644
--- a/test/cmp5.go
+++ b/test/cmp5.go
@@ -8,7 +8,7 @@
 
 func main()
 {
-	var b map[string]int;
+	var b []int;
 	var ib interface{} = b;
 	var m = make(map[interface{}] int);
 	m[ib] = 1;