Pass instruction set variant to dex2oat.

Also, add it to the ANDROID_BUILD_PROPERTIES.
Remove non-default instruction set features.
Bug: 18056890

Change-Id: I9169cdfecbb176f62b941852948222edc3f511fd
diff --git a/core/dex_preopt_libart.mk b/core/dex_preopt_libart.mk
index b61b180..d064e8c 100644
--- a/core/dex_preopt_libart.mk
+++ b/core/dex_preopt_libart.mk
@@ -97,6 +97,7 @@
 	--oat-file=$(2) \
 	--android-root=$(PRODUCT_OUT)/system \
 	--instruction-set=$($(PRIVATE_2ND_ARCH_VAR_PREFIX)DEX2OAT_TARGET_ARCH) \
+	--instruction-set-variant=$($(PRIVATE_2ND_ARCH_VAR_PREFIX)DEX2OAT_TARGET_CPU_VARIANT) \
 	--instruction-set-features=$($(PRIVATE_2ND_ARCH_VAR_PREFIX)DEX2OAT_TARGET_INSTRUCTION_SET_FEATURES) \
 	--include-patch-information --runtime-arg -Xnorelocate --no-include-debug-symbols \
 	$(PRIVATE_DEX_PREOPT_FLAGS)