pkg/file: Fix file.Glob to generate correct CUE structure

Closes #274
https://github.com/cuelang/cue/pull/274

GitOrigin-RevId: 45842b704d09c6a267de32664eda73a052d1bb7b
Change-Id: I3cf7077aa2c1987c18f9fddd013e8b005dc2280b
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/4880
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
diff --git a/pkg/tool/file/file.go b/pkg/tool/file/file.go
index b0d1e23..7514a03 100644
--- a/pkg/tool/file/file.go
+++ b/pkg/tool/file/file.go
@@ -107,5 +107,6 @@
 	for i, s := range m {
 		m[i] = filepath.ToSlash(s)
 	}
-	return m, err
+	files := map[string]interface{}{"files": m}
+	return files, err
 }
diff --git a/pkg/tool/file/file_test.go b/pkg/tool/file/file_test.go
index 6dfb17f..c9bc38f 100644
--- a/pkg/tool/file/file_test.go
+++ b/pkg/tool/file/file_test.go
@@ -133,8 +133,7 @@
 	if err != nil {
 		t.Fatal(err)
 	}
-
-	if want := []string{"testdata/input.foo"}; !reflect.DeepEqual(got, want) {
+	if want := map[string]interface{}{"files": []string{"testdata/input.foo"}}; !reflect.DeepEqual(got, want) {
 		t.Errorf("got %v; want %v", got, want)
 	}
 }