ART: Change the isa defaults for Mips

Select the correct cpu variant for ART and select the default
features based on compile flags for when the variant is not
defined.

Change-Id: I13622db85446ed6fbb467a699d8d3e27833f6f88
diff --git a/build/Android.oat.mk b/build/Android.oat.mk
index 4d2fa41..710b130 100644
--- a/build/Android.oat.mk
+++ b/build/Android.oat.mk
@@ -230,6 +230,7 @@
 	  $$(addprefix --dex-location=,$$(TARGET_CORE_DEX_LOCATIONS)) --oat-file=$$(PRIVATE_CORE_OAT_NAME) \
 	  --oat-location=$$(PRIVATE_CORE_OAT_NAME) --image=$$(PRIVATE_CORE_IMG_NAME) \
 	  --base=$$(LIBART_IMG_TARGET_BASE_ADDRESS) --instruction-set=$$($(3)TARGET_ARCH) \
+	  --instruction-set-variant=$$($(3)DEX2OAT_TARGET_CPU_VARIANT) \
 	  --instruction-set-features=$$($(3)DEX2OAT_TARGET_INSTRUCTION_SET_FEATURES) \
 	  --android-root=$$(PRODUCT_OUT)/system --include-patch-information \
 	  $$(PRIVATE_CORE_COMPILE_OPTIONS) || (rm $$(PRIVATE_CORE_OAT_NAME); exit 1)