os: clean up after TestIssue60181

This test currently leaves two temp files lying around - ensure these
are created in the current working directory (a temp dir) so that they
get cleaned up when the test is complete.

Change-Id: I9a29e24a2cd601de3ab39c421830ee2bcda76516
Reviewed-on: https://go-review.googlesource.com/c/go/+/597317
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Auto-Submit: Ian Lance Taylor <[email protected]>

Author: 4a6f656c

src/os/os_unix_test.go

@@ -376,14 +376,14 @@ func TestIssue60181(t *testing.T) {
 
 	want := "hello gopher"
 
-	a, err := CreateTemp("", "a")
+	a, err := CreateTemp(".", "a")
 	if err != nil {
 		t.Fatal(err)
 	}
 	a.WriteString(want[:5])
 	a.Close()
 
-	b, err := CreateTemp("", "b")
+	b, err := CreateTemp(".", "b")
 	if err != nil {
 		t.Fatal(err)
 	}