Build: Move preopt classpath to private variable

Move DEX2OAT_CLASS_LOADER_CONTEXT to
PRIVATE_DEX2OAT_CLASS_LOADER_CONTEXT in preparation for actual
classpaths.

Bug: 65256727
Test: m
Test: oatdump --oat-file=$OUT/system/framework/oat/arm64/wifi-service.odex --header-only
Change-Id: I5bcfebcd3be1a187954f550dbe1d3aa1d5099052
diff --git a/core/dex_preopt_libart.mk b/core/dex_preopt_libart.mk
index aa11d15..1070ebe 100644
--- a/core/dex_preopt_libart.mk
+++ b/core/dex_preopt_libart.mk
@@ -11,10 +11,6 @@
 DEX2OAT := $(HOST_OUT_EXECUTABLES)/dex2oatd$(HOST_EXECUTABLE_SUFFIX)
 endif
 
-# Pass special class loader context to skip the classpath and collision check.
-# Should modify build system to pass used libraries properly later.
-DEX2OAT_CLASS_LOADER_CONTEXT := "&"
-
 DEX2OAT_DEPENDENCY += $(DEX2OAT)
 
 # Use the first preloaded-classes file in PRODUCT_COPY_FILES.
@@ -150,7 +146,7 @@
 $(hide) mkdir -p $(dir $(2))
 $(hide) ANDROID_LOG_TAGS="*:e" $(DEX2OAT) \
 	--runtime-arg -Xms$(DEX2OAT_XMS) --runtime-arg -Xmx$(DEX2OAT_XMX) \
-	--class-loader-context=$(DEX2OAT_CLASS_LOADER_CONTEXT) \
+	--class-loader-context=$(PRIVATE_DEX2OAT_CLASS_LOADER_CONTEXT) \
 	--boot-image=$(PRIVATE_DEX_PREOPT_IMAGE_LOCATION) \
 	--dex-file=$(1) \
 	--dex-location=$(PRIVATE_DEX_LOCATION) \