libdiskconfig: add missing LOCAL_MODULE_TAGS

Change-Id: Ia4fceb4e4f33df3e37b0e83f042fff09dab2d06c
diff --git a/libdiskconfig/Android.mk b/libdiskconfig/Android.mk
index c887955..714606a 100644
--- a/libdiskconfig/Android.mk
+++ b/libdiskconfig/Android.mk
@@ -12,6 +12,7 @@
 include $(CLEAR_VARS)
 LOCAL_SRC_FILES := $(commonSources)
 LOCAL_MODULE := libdiskconfig
+LOCAL_MODULE_TAGS := optional
 LOCAL_SYSTEM_SHARED_LIBRARIES := libcutils liblog libc
 include $(BUILD_SHARED_LIBRARY)
 
@@ -19,6 +20,7 @@
 include $(CLEAR_VARS)
 LOCAL_SRC_FILES := $(commonSources)
 LOCAL_MODULE := libdiskconfig_host
+LOCAL_MODULE_TAGS := optional
 LOCAL_SYSTEM_SHARED_LIBRARIES := libcutils
 LOCAL_CFLAGS := -O2 -g -W -Wall -Werror -D_LARGEFILE64_SOURCE
 include $(BUILD_HOST_STATIC_LIBRARY)