Support to check System API.

Change-Id: I60f8c9bb13efb6a440bb735d634f63fab035c810
diff --git a/core/config.mk b/core/config.mk
index 64dc68e..c4d088d 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -43,6 +43,7 @@
 SRC_SERVERS:= $(TOPDIR)servers
 SRC_TARGET_DIR := $(TOPDIR)build/target
 SRC_API_DIR := $(TOPDIR)prebuilts/sdk/api
+SRC_SYSTEM_API_DIR := $(TOPDIR)prebuilts/sdk/system-api
 
 # Some specific paths to tools
 SRC_DROIDDOC_DIR := $(TOPDIR)build/tools/droiddoc
@@ -587,6 +588,8 @@
 
 INTERNAL_PLATFORM_API_FILE := $(TARGET_OUT_COMMON_INTERMEDIATES)/PACKAGING/public_api.txt
 INTERNAL_PLATFORM_REMOVED_API_FILE := $(TARGET_OUT_COMMON_INTERMEDIATES)/PACKAGING/removed.txt
+INTERNAL_PLATFORM_SYSTEM_API_FILE := $(TARGET_OUT_COMMON_INTERMEDIATES)/PACKAGING/system-api.txt
+INTERNAL_PLATFORM_SYSTEM_REMOVED_API_FILE := $(TARGET_OUT_COMMON_INTERMEDIATES)/PACKAGING/system-removed.txt
 
 # This is the standard way to name a directory containing prebuilt target
 # objects. E.g., prebuilt/$(TARGET_PREBUILT_TAG)/libc.so