Revive sepolicy module

Although it's not needed for Treblized devices, some targets are still
requiring it due to PRODUCT_SEPOLICY_SPLIT := false. To mitigate build
breakage, this change revives the sepolicy module.

Bug: 211936491
Test: build/soong/soong_ui.bash --make-mode dist \
    TARGET_PRODUCT=bertha_x86_64 ndk_translation_all
Change-Id: Ie64c223db8900967cfb54897f5366ad5ef13d4d9
diff --git a/Android.mk b/Android.mk
index 4eecbb4..0ef4f0b 100644
--- a/Android.mk
+++ b/Android.mk
@@ -743,6 +743,24 @@
 built_sepolicy := $(call intermediates-dir-for,ETC,precompiled_sepolicy)/precompiled_sepolicy
 
 #################################
+# sepolicy is also built with Android.bp.
+# This module is to keep compatibility with monolithic sepolicy devices.
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := sepolicy
+LOCAL_LICENSE_KINDS := SPDX-license-identifier-Apache-2.0 legacy_unencumbered
+LOCAL_LICENSE_CONDITIONS := notice unencumbered
+LOCAL_NOTICE_FILE := $(LOCAL_PATH)/NOTICE
+LOCAL_MODULE_CLASS := ETC
+LOCAL_MODULE_TAGS := optional
+LOCAL_MODULE_PATH := $(TARGET_ROOT_OUT)
+
+include $(BUILD_SYSTEM)/base_rules.mk
+
+$(LOCAL_BUILT_MODULE): $(built_sepolicy)
+	$(copy-file-to-target)
+
+#################################
 include $(CLEAR_VARS)
 
 # keep concrete sepolicy for neverallow checks