Revert^4 "add rust_toolchain_rustc_prebuilt module type"

930fd8bfb1190e20789c332d3f8d7de79bcee13c

Change-Id: Id3f3a66022a496aab7db93670a7bdf8507384875
diff --git a/cc/testing.go b/cc/testing.go
index 7531f6d..71d986b 100644
--- a/cc/testing.go
+++ b/cc/testing.go
@@ -35,6 +35,7 @@
 
 	multitree.RegisterApiImportsModule(ctx)
 
+	ctx.RegisterModuleType("prebuilt_build_tool", android.NewPrebuiltBuildTool)
 	ctx.RegisterModuleType("cc_benchmark", BenchmarkFactory)
 	ctx.RegisterModuleType("cc_object", ObjectFactory)
 	ctx.RegisterModuleType("cc_genrule", GenRuleFactory)