Handle product_variable asflag for cc_object.

cc_object crtbrand sets product_variable.platform_sdk_version.asflag
and will not compile correctly within mixed builds without it.

Only handles product_variables that expand product variables.

Bug: 181794963
Test: ~/aosp/build/bazel/scripts/milestone-2/demo.sh full
Change-Id: I293fcb18032aa51f63bb7b3de94abd6d1ec38180
diff --git a/android/mutator.go b/android/mutator.go
index 9552aa1..051873b 100644
--- a/android/mutator.go
+++ b/android/mutator.go
@@ -539,7 +539,7 @@
 		Name: &name,
 	}
 
-	b := t.CreateModule(factory, &nameProp, attrs).(BazelTargetModule)
+	b := t.createModuleWithoutInheritance(factory, &nameProp, attrs).(BazelTargetModule)
 	b.SetBazelTargetModuleProperties(bazelProps)
 	return b
 }
@@ -608,6 +608,11 @@
 	return module
 }
 
+func (t *topDownMutatorContext) createModuleWithoutInheritance(factory ModuleFactory, props ...interface{}) Module {
+	module := t.bp.CreateModule(ModuleFactoryAdaptor(factory), props...).(Module)
+	return module
+}
+
 func (b *bottomUpMutatorContext) MutatorName() string {
 	return b.bp.MutatorName()
 }