Also create dirs under /first_stage_ramdisk for GKI.

If the device uses GKI and generic ramdisk, also create
empty directories under /first_stage_ramdisk so that they
won't have to be created at runtime. This allows generic
ramdisk to be not writable.

Test: boots
Bug: 173425293
Change-Id: If987cb1d4af9f9ee94a43a4523f9e1465b01b16a
diff --git a/init/Android.mk b/init/Android.mk
index cf504ed..5336425 100644
--- a/init/Android.mk
+++ b/init/Android.mk
@@ -85,6 +85,9 @@
     sys \
 
 LOCAL_POST_INSTALL_CMD := mkdir -p $(addprefix $(TARGET_RAMDISK_OUT)/,$(my_ramdisk_dirs))
+ifeq (true,$(BOARD_USES_GENERIC_KERNEL_IMAGE))
+    LOCAL_POST_INSTALL_CMD += $(addprefix $(TARGET_RAMDISK_OUT)/first_stage_ramdisk/,$(my_ramdisk_dirs))
+endif
 
 my_ramdisk_dirs :=