Use on_vendor VNDK APEX for non-REL build

For non-REL branch, move VNDK APEX to /vendor partition so we don't need
to update vendor.img prebuilt everytime there is a change in the VNDK
libraries.
For REL branch, the API/ABI surfaces of VNDK libraries are frozen so
don't need to move to /vendor partition.

Bug: 140136207
Test: Build on REL and non-REL branch
Change-Id: Ibce24465b546c52bc447b4b28a474de2b4b53792
diff --git a/aosp_raven.mk b/aosp_raven.mk
index f434886..18da783 100644
--- a/aosp_raven.mk
+++ b/aosp_raven.mk
@@ -26,4 +26,8 @@
 PRODUCT_BRAND_FOR_ATTESTATION := google
 PRODUCT_MANUFACTURER := Google
 
-PRODUCT_PACKAGES += com.android.vndk.current.on_vendor
+# Keep the VNDK APEX in /system partition for REL branches as these branches are
+# expected to have stable API/ABI surfaces.
+ifneq (REL,$(PLATFORM_VERSION_CODENAME))
+  PRODUCT_PACKAGES += com.android.vndk.current.on_vendor
+endif