Fix llndk_library init

llndk_library modules were not calling module.Init(), which caused them
not to register ModuleBase.VendorProperties.  Unregistered property
structs lose their values during cloning, which caused the shared
variants of llndk_library modules to not have IsLLNDK set.

Call module.Init(), which registers ModuleBase.VendorProperties.  Also
add a helper function to filter out llndk_library modules that now
show up in the list of modules with IsLLNDK set.

Bug: 170784825
Test: m checkbuild
Change-Id: Iafde85f6a95e85a618f6f7d7a210398febb6b158
diff --git a/cc/llndk_library.go b/cc/llndk_library.go
index d0fbc48..0c4bcfd 100644
--- a/cc/llndk_library.go
+++ b/cc/llndk_library.go
@@ -100,6 +100,11 @@
 	return name + llndkLibrarySuffix
 }
 
+func (stub *llndkStubDecorator) linkerProps() []interface{} {
+	props := stub.libraryDecorator.linkerProps()
+	return append(props, &stub.Properties)
+}
+
 func (stub *llndkStubDecorator) linkerFlags(ctx ModuleContext, flags Flags) Flags {
 	stub.libraryDecorator.libName = stub.implementationModuleName(ctx.ModuleName())
 	return stub.libraryDecorator.linkerFlags(ctx, flags)
@@ -137,12 +142,6 @@
 	module.installer = nil
 	module.library = stub
 
-	module.AddProperties(
-		&module.Properties,
-		&stub.Properties,
-		&library.MutatedProperties,
-		&library.flagExporter.Properties)
-
 	return module
 }
 
@@ -156,8 +155,14 @@
 //    }
 func LlndkLibraryFactory() android.Module {
 	module := NewLLndkStubLibrary()
-	android.InitAndroidArchModule(module, android.DeviceSupported, android.MultilibBoth)
-	return module
+	return module.Init()
+}
+
+// isVestigialLLNDKModule returns true if m is a vestigial llndk_library module used to provide
+// properties to the LLNDK variant of a cc_library.
+func isVestigialLLNDKModule(m *Module) bool {
+	_, ok := m.linker.(*llndkStubDecorator)
+	return ok
 }
 
 type llndkHeadersDecorator struct {