Allow cc_object modules to use STL

cc_object modules may need access to the STL headers.

Test: m checkbuild
Change-Id: I88ad556a349d9530d24949f05eebf8b6fab4c62a

cc/object.go

@@ -39,6 +39,7 @@ func objectFactory() android.Module {
 		baseLinker: NewBaseLinker(nil),
 	}
 	module.compiler = NewBaseCompiler()
+	module.stl = &stl{}
 	return module.Init()
 }