rootdir: Add modules directory

... as the mount point for the modules partition. If
the partition does not exist, just leave the directory
empty.

Test: on CF check /proc/mounts
Bug: 163543381
Change-Id: I2fa96199a029179395a2d655937728f4275ba2b3
diff --git a/rootdir/Android.mk b/rootdir/Android.mk
index 77fa94e..81dba1f 100644
--- a/rootdir/Android.mk
+++ b/rootdir/Android.mk
@@ -141,6 +141,9 @@
 # via /odm/lib/modules directly.
 LOCAL_POST_INSTALL_CMD += ; ln -sf /odm/odm_dlkm/etc $(TARGET_ROOT_OUT)/odm_dlkm/etc
 
+# For /modules partition.
+LOCAL_POST_INSTALL_CMD += ; mkdir -p $(TARGET_ROOT_OUT)/modules
+
 ifdef BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE
   LOCAL_POST_INSTALL_CMD += ; mkdir -p $(TARGET_ROOT_OUT)/cache
 else