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/prebuilt.go b/cc/prebuilt.go
index d064a46..ac05df0 100644
--- a/cc/prebuilt.go
+++ b/cc/prebuilt.go
@@ -16,8 +16,6 @@
 
 import (
 	"android/soong/android"
-
-	"github.com/google/blueprint"
 )
 
 func init() {
@@ -65,7 +63,7 @@
 	return nil
 }
 
-func prebuiltSharedLibraryFactory() (blueprint.Module, []interface{}) {
+func prebuiltSharedLibraryFactory() android.Module {
 	module, _ := NewPrebuiltSharedLibrary(android.HostAndDeviceSupported)
 	return module.Init()
 }
@@ -83,7 +81,7 @@
 	return module, library
 }
 
-func prebuiltStaticLibraryFactory() (blueprint.Module, []interface{}) {
+func prebuiltStaticLibraryFactory() android.Module {
 	module, _ := NewPrebuiltStaticLibrary(android.HostAndDeviceSupported)
 	return module.Init()
 }
@@ -124,7 +122,7 @@
 	return nil
 }
 
-func prebuiltBinaryFactory() (blueprint.Module, []interface{}) {
+func prebuiltBinaryFactory() android.Module {
 	module, _ := NewPrebuiltBinary(android.HostAndDeviceSupported)
 	return module.Init()
 }