Add a new variable for deprecating VNDK

Add a new flag variable for deprecating VNDK. This variable should be
passed to Soong, so it can change behavior based on the flag.

Bug: 290157355
Test: build succeeded with KEEP_VNDK=false
Change-Id: I3a9d1041411ad24ff42f76506a8f929e364b868d
diff --git a/core/main.mk b/core/main.mk
index 5a591f9..b2d0699 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -218,6 +218,12 @@
   else
     ADDITIONAL_VENDOR_PROPERTIES := ro.vndk.version=$(BOARD_VNDK_VERSION)
   endif
+
+  # TODO(b/290159430): ro.vndk.deprecate is a temporal variable for deprecating VNDK.
+  # This variable will be removed once ro.vndk.version can be removed.
+  ifneq ($(KEEP_VNDK),true)
+    ADDITIONAL_SYSTEM_PROPERTIES += ro.vndk.deprecate=true
+  endif
 endif
 
 # Add cpu properties for bionic and ART.