update_verifier: skip verity to determine successful on custom builds

Change-Id: I27a89df652febb312971a9afdb4dc37f8adb0b2e
diff --git a/update_verifier/Android.mk b/update_verifier/Android.mk
index 0ff8854..2f9dda1 100644
--- a/update_verifier/Android.mk
+++ b/update_verifier/Android.mk
@@ -39,9 +39,11 @@
 LOCAL_C_INCLUDES := \
     $(LOCAL_PATH)/include
 
+ifeq ($(CUSTOM_BUILD),)
 ifeq ($(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_SUPPORTS_VERITY),true)
 LOCAL_CFLAGS += -DPRODUCT_SUPPORTS_VERITY=1
 endif
+endif
 
 ifeq ($(BOARD_AVB_ENABLE),true)
 LOCAL_CFLAGS += -DBOARD_AVB_ENABLE=1