Add verity support to `make dist`.

Without this, system images will be built that do not contain the
necessary bits for verification.

Change-Id: I87c15282b26377d7a2a1540e3d0e30b0299622e3
diff --git a/core/product.mk b/core/product.mk
index 1a7685c..5693fe9 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -104,7 +104,8 @@
     PRODUCT_OEM_PROPERTIES \
     PRODUCT_SYSTEM_PROPERTY_BLACKLIST \
     PRODUCT_VERITY_PARTITION \
-    PRODUCT_VERITY_SIGNING_KEY
+    PRODUCT_VERITY_SIGNING_KEY \
+    PRODUCT_VERITY_MOUNTPOINT
 
 define dump-product
 $(info ==== $(1) ====)\