Stash TARGET_CPU_VARIANT and print it in dumpvar.

Bug:7961327
Change-Id: I8a3637a87b5a0f791568fe74e44a4a173541deb7
diff --git a/core/product.mk b/core/product.mk
index b934826..bbd0c31 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -209,6 +209,7 @@
 _product_stash_var_list := $(_product_var_list) \
 	TARGET_ARCH \
 	TARGET_ARCH_VARIANT \
+	TARGET_CPU_VARIANT \
 	TARGET_BOARD_PLATFORM \
 	TARGET_BOARD_PLATFORM_GPU \
 	TARGET_BOARD_KERNEL_HEADERS \