Support for recovery snapshot.

Bug: 171231437
Test: source build/envsetup.sh
Test: ALLOW_MISSING_DEPENDENCIES=true m -j nothing

Change-Id: I6b35fbb0b90ffffa941ea108cbd31a454b2dd403
diff --git a/cc/testing.go b/cc/testing.go
index 388a9ce..fa2c25c 100644
--- a/cc/testing.go
+++ b/cc/testing.go
@@ -563,6 +563,7 @@
 	RegisterRequiredBuildComponentsForTest(ctx)
 	ctx.RegisterSingletonType("vndk-snapshot", VndkSnapshotSingleton)
 	ctx.RegisterSingletonType("vendor-snapshot", VendorSnapshotSingleton)
+	ctx.RegisterSingletonType("recovery-snapshot", RecoverySnapshotSingleton)
 
 	return ctx
 }