For 64-bit, use 32-bit DEXPREOPT if zygote64 isn't enabled.

Change-Id: Ia95d74517f8182031d6044ae55559010a98ec5ca
diff --git a/core/dex_preopt_libart.mk b/core/dex_preopt_libart.mk
index 7809c13..73e8494 100644
--- a/core/dex_preopt_libart.mk
+++ b/core/dex_preopt_libart.mk
@@ -69,7 +69,8 @@
 		--oat-file=$(patsubst %.art,%.oat,$@) \
 		--oat-location=$(patsubst %.art,%.oat,$(LIBART_BOOT_IMAGE)) \
 		--image=$@ --base=$(LIBART_IMG_TARGET_BASE_ADDRESS) \
-		--instruction-set=$(TARGET_ARCH) --instruction-set-features=$(DEX2OAT_TARGET_INSTRUCTION_SET_FEATURES) \
+		--instruction-set=$(DEX2OAT_TARGET_ARCH) \
+		--instruction-set-features=$(DEX2OAT_TARGET_INSTRUCTION_SET_FEATURES) \
 		--android-root=$(PRODUCT_OUT)/system
 
 
@@ -90,6 +91,6 @@
 	--dex-location=$(3) \
 	--oat-file=$(4) \
 	--android-root=$(PRODUCT_OUT)/system \
-	--instruction-set=$(TARGET_ARCH) \
+	--instruction-set=$(DEX2OAT_TARGET_ARCH) \
 	--instruction-set-features=$(DEX2OAT_TARGET_INSTRUCTION_SET_FEATURES)
 endef