bloaty: measure stripped Rust binaries

Modify bloaty's MeasureSizeForPath to allow a module to provide multiple
paths. This is used to measure both unstripped and stripped
libraries/binaries. Add unit test to ensure correct measurements are
generated for Rust.

Test: m out/soong/binary_sizes.pb.gz
Change-Id: I59439b77dbf1cf5ad71e1c02996a6a90938536b4

bloaty/testing.go

@@ -0,0 +1,25 @@
+// Copyright 2021 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package bloaty
+
+import (
+	"android/soong/android"
+)
+
+// Preparer that will define the default bloaty singleton.
+var PrepareForTestWithBloatyDefaultModules = android.GroupFixturePreparers(
+	android.FixtureRegisterWithContext(func(ctx android.RegistrationContext) {
+		ctx.RegisterSingletonType("file_metrics", fileSizesSingleton)
+	}))