Enable bloaty artifact for checkbuild

Test: m checkbuild dist; verify DIST_DIR/binary_sizes.pb
Bug: 172339742
Change-Id: If6f3b33a5d6efade98a15ddf5827ef010d1535dd
diff --git a/bloaty/bloaty.go b/bloaty/bloaty.go
index 0bff8aa..21bf4ac 100644
--- a/bloaty/bloaty.go
+++ b/bloaty/bloaty.go
@@ -23,6 +23,7 @@
 )
 
 const bloatyDescriptorExt = "bloaty.csv"
+const protoFilename = "binary_sizes.pb"
 
 var (
 	fileSizeMeasurerKey blueprint.ProviderKey
@@ -87,6 +88,10 @@
 	ctx.Build(pctx, android.BuildParams{
 		Rule:   bloatyMerger,
 		Inputs: android.SortedUniquePaths(deps),
-		Output: android.PathForOutput(ctx, "binary_sizes.pb"),
+		Output: android.PathForOutput(ctx, protoFilename),
 	})
 }
+
+func (singleton *sizesSingleton) MakeVars(ctx android.MakeVarsContext) {
+	ctx.DistForGoalWithFilename("checkbuild", android.PathForOutput(ctx, protoFilename), protoFilename)
+}