Add a graph coloring art test option

Test: ART_TEST_OPTIMIZING_GRAPH_COLOR=true m test-art-host

Change-Id: I1bd7c20cdd372ed227204c990484d123c67bdfa8
diff --git a/build/Android.common_test.mk b/build/Android.common_test.mk
index df7df26..93e310e 100644
--- a/build/Android.common_test.mk
+++ b/build/Android.common_test.mk
@@ -57,6 +57,9 @@
 # Do you want optimizing compiler tests run?
 ART_TEST_OPTIMIZING ?= true
 
+# Do you want to test the optimizing compiler with graph coloring register allocation?
+ART_TEST_OPTIMIZING_GRAPH_COLOR ?= $(ART_TEST_FULL)
+
 # Do we want to test a PIC-compiled core image?
 ART_TEST_PIC_IMAGE ?= $(ART_TEST_FULL)