Refactor factories

Change module factories from returning a blueprint.Module and a list
of property structs to returning an android.Module, which holds the
list of property structs.

Test: build.ninja identical except for Factory: comment lines
Change-Id: Ica1d823f009db812c518f271a386fbff39c9766f
diff --git a/cc/toolchain_library.go b/cc/toolchain_library.go
index 1bbe774..9b83f18 100644
--- a/cc/toolchain_library.go
+++ b/cc/toolchain_library.go
@@ -15,7 +15,6 @@
 package cc
 
 import (
-	"github.com/google/blueprint"
 	"github.com/google/blueprint/proptools"
 
 	"android/soong/android"
@@ -38,7 +37,7 @@
 	return deps
 }
 
-func toolchainLibraryFactory() (blueprint.Module, []interface{}) {
+func toolchainLibraryFactory() android.Module {
 	module, library := NewLibrary(android.HostAndDeviceSupported)
 	library.BuildOnlyStatic()
 	toolchainLibrary := &toolchainLibraryDecorator{