Declare variable for all art oat tests

Change-Id: If0795928ab08bbce80479eec32b987662631b8cf
diff --git a/test/Android.mk b/test/Android.mk
index 6e37af3..9b79abf 100644
--- a/test/Android.mk
+++ b/test/Android.mk
@@ -110,6 +110,7 @@
 
 # Used outside the art project to get a list of the current tests
 ART_TEST_DEX_MAKE_TARGETS := $(addprefix art-test-dex-, $(TEST_DEX_DIRECTORIES))
+ART_TEST_OAT_MAKE_TARGETS := $(addprefix oat-test-dex-, $(TEST_OAT_DIRECTORIES))
 
 # Rules to explicitly create 2nd-arch test directories, as we use a "cp" for them
 # instead of BUILD_JAVA_LIBRARY