Match gccgo error messages.

bug205.go:14:12: error: index must be integer
bug205.go:15:12: error: index must be integer
bug205.go:16:12: error: incompatible type for map index

R=rsc
DELTA=2  (0 added, 0 deleted, 2 changed)
OCL=35957
CL=35960

test/fixedbugs/bug205.go

@@ -11,8 +11,8 @@ var s string;
 var m map[string]int;
 
 func main() {
-	println(t["hi"]);	// ERROR "non-integer"
-	println(s["hi"]);	// ERROR "non-integer"
+	println(t["hi"]);	// ERROR "integer"
+	println(s["hi"]);	// ERROR "integer"
 	println(m[0]);	// ERROR "map index"
 }