Rename PRODUCT_USES_ART to PRODUCT_USES_DEFAULT_ART_CONFIG

It better describes what is meant to represent.

Test: m build
Change-Id: I942721cee2c7eaef625bf8c64aae32c1725705eb
diff --git a/core/dex_preopt.mk b/core/dex_preopt.mk
index 180edaf..32690fe 100644
--- a/core/dex_preopt.mk
+++ b/core/dex_preopt.mk
@@ -26,7 +26,7 @@
 # We can do this only if preopt is enabled and if the product uses libart config (which sets the
 # default properties for preopting).
 ifeq ($(WITH_DEXPREOPT), true)
-ifeq ($(PRODUCT_USES_ART), true)
+ifeq ($(PRODUCT_USES_DEFAULT_ART_CONFIG), true)
 
 boot_zip := $(PRODUCT_OUT)/boot.zip
 bootclasspath_jars := $(DEXPREOPT_BOOTCLASSPATH_DEX_FILES)
@@ -45,5 +45,5 @@
 
 $(call dist-for-goals, droidcore, $(boot_zip))
 
-endif  #PRODUCT_USES_ART
+endif  #PRODUCT_USES_DEFAULT_ART_CONFIG
 endif  #WITH_DEXPREOPT