Make /apex on ramdisk

Bug: 127576519
Bug: 127653919
Test: build hikey, check ramdisk has /apex directory
Change-Id: I4e844caa032c0717bd36d323675852ce3681fb01
diff --git a/init/Android.mk b/init/Android.mk
index ac05542..cc514ed 100644
--- a/init/Android.mk
+++ b/init/Android.mk
@@ -63,8 +63,9 @@
 LOCAL_UNSTRIPPED_PATH := $(TARGET_RAMDISK_OUT_UNSTRIPPED)
 
 # Set up the same mount points on the ramdisk that system-as-root contains.
-LOCAL_POST_INSTALL_CMD := \
-    mkdir -p $(TARGET_RAMDISK_OUT)/dev \
+LOCAL_POST_INSTALL_CMD := mkdir -p \
+    $(TARGET_RAMDISK_OUT)/apex \
+    $(TARGET_RAMDISK_OUT)/dev \
     $(TARGET_RAMDISK_OUT)/mnt \
     $(TARGET_RAMDISK_OUT)/proc \
     $(TARGET_RAMDISK_OUT)/sys \