Add LOCAL_VENDOR_MODULE as a synonym to LOCAL_PROPRIETARY_MODULE

The vendor image will have more than just proprietary modules in it
under Treble, so let's stop marking open source code as proprietary just
to move it to vendor.

Bug: 36452052
Test: compare build-aosp_arm.ninja before/after, no changes.
Test: Try defining LOCAL_VENDOR_MODULE / LOCAL_PROPRIETARY_MODULE in the
same and different ways, ensure it works.
Change-Id: I0ab046bcb7563a20d44ed00667e18497ef0873a8
diff --git a/core/Makefile b/core/Makefile
index cf0aa4a..ab88b90 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1355,7 +1355,7 @@
 	  $(hide) echo "PDK.DEXPREOPT.$(m).MULTILIB:=$(DEXPREOPT.$(m).MULTILIB)" >> $@$(newline)\
 	  $(hide) echo "PDK.DEXPREOPT.$(m).DEX_PREOPT_FLAGS:=$(DEXPREOPT.$(m).DEX_PREOPT_FLAGS)" >> $@$(newline)\
 	  $(hide) echo "PDK.DEXPREOPT.$(m).PRIVILEGED_MODULE:=$(DEXPREOPT.$(m).PRIVILEGED_MODULE)" >> $@$(newline)\
-	  $(hide) echo "PDK.DEXPREOPT.$(m).PROPRIETARY_MODULE:=$(DEXPREOPT.$(m).PROPRIETARY_MODULE)" >> $@$(newline)\
+	  $(hide) echo "PDK.DEXPREOPT.$(m).VENDOR_MODULE:=$(DEXPREOPT.$(m).VENDOR_MODULE)" >> $@$(newline)\
 	  $(hide) echo "PDK.DEXPREOPT.$(m).TARGET_ARCH:=$(DEXPREOPT.$(m).TARGET_ARCH)" >> $@$(newline)\
 	  $(hide) echo "PDK.DEXPREOPT.$(m).STRIPPED_SRC:=$(patsubst $(PRODUCT_OUT)/%,%,$(DEXPREOPT.$(m).INSTALLED_STRIPPED))" >> $@$(newline)\
 	  )