Don't fork dex2oat process on target device.

Change-Id: I35370d328aaa1aaaed5b56e62e51c4c74afa9cba
diff --git a/build/Android.common.mk b/build/Android.common.mk
index 8f41c24..c950298 100644
--- a/build/Android.common.mk
+++ b/build/Android.common.mk
@@ -66,7 +66,7 @@
 
 ART_HOST_CFLAGS := $(art_cflags) -DANDROID_SMP=1
 
-ART_TARGET_CFLAGS := $(art_cflags)
+ART_TARGET_CFLAGS := $(art_cflags) -DART_TARGET
 ifeq ($(TARGET_CPU_SMP),true)
   ART_TARGET_CFLAGS += -DANDROID_SMP=1
 else