Add adb keys to debuggable AOSP builds

These don't exist on AOSP itself, but if they're added in, debuggable
builds will include the keys. This way automated test farms don't need
manual intervention to authenticate to the device over adb, but we don't
disable security for everyone else.

Bug: 32891559
Test: lunch aosp_marlin-userdebug; m
Change-Id: I59011a5c1f45b0c8bd5c2355d2b4c3671f5da4e4
diff --git a/target/product/full_base.mk b/target/product/full_base.mk
index f2652eb..7aac435 100644
--- a/target/product/full_base.mk
+++ b/target/product/full_base.mk
@@ -53,3 +53,6 @@
 
 # Get everything else from the parent package
 $(call inherit-product, $(SRC_TARGET_DIR)/product/generic_no_telephony.mk)
+
+# Add adb keys to debuggable AOSP builds (if they exist)
+$(call inherit-product-if-exists, vendor/google/security/adb/vendor_key.mk)