runtime: rename the TestGcHashmapIndirection to TestGcMapIndirection

There was still the word 'Hashmap' in gc_test.go, so I renamed it to just 'Map'

Previous renaming commit: https://golang.org/cl/90336

Change-Id: I5b0e5c2229d1c30937c7216247f4533effb81ce7
Reviewed-on: https://go-review.googlesource.com/96675Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/runtime/gc_test.go

@@ -43,7 +43,7 @@ func TestGcDeepNesting(t *testing.T) {
 	}
 }
 
-func TestGcHashmapIndirection(t *testing.T) {
+func TestGcMapIndirection(t *testing.T) {
 	defer debug.SetGCPercent(debug.SetGCPercent(1))
 	runtime.GC()
 	type T struct {