bp2build: cc_library_headers converter should only include that module type

Test: bp2build; bazel build //bionic/...
Change-Id: I34768b51098c5b801e7c6d9b3a95ec0f37c3bb09

cc/library_headers.go

@@ -90,16 +90,12 @@ func CcLibraryHeadersBp2Build(ctx android.TopDownMutatorContext) {
 		return
 	}
 
-	lib, ok := module.linker.(*libraryDecorator)
-	if !ok {
-		// Not a cc_library module
-		return
-	}
-	if !lib.header() {
-		// Not a cc_library_headers module
+	if ctx.ModuleType() != "cc_library_headers" {
 		return
 	}
 
+	lib, _ := module.linker.(*libraryDecorator)
+
 	// list of directories that will be added to the include path (using -I) for this
 	// module and any module that links against this module.
 	includeDirs := lib.flagExporter.Properties.Export_system_include_dirs