Add extra_test_configs option support in mk

Bug: 163344047
Test: m -j HelloWorldHostTest hello_world_test HelloWorldTests
Change-Id: Ie63c2a80e01984ac9941d0bad4ad7948e0bb8ac0
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index 307c2c2..288c855 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -98,6 +98,7 @@
 LOCAL_EXPORT_SDK_LIBRARIES:=
 LOCAL_EXPORT_SHARED_LIBRARY_HEADERS:=
 LOCAL_EXPORT_STATIC_LIBRARY_HEADERS:=
+LOCAL_EXTRA_FULL_TEST_CONFIGS:=
 LOCAL_EXTRACT_APK:=
 LOCAL_EXTRACT_DPI_APK:=
 LOCAL_FDO_SUPPORT:=