Stash TARGET_CPU_VARIANT and print it in dumpvar.

Bug:7961327
Change-Id: I8a3637a87b5a0f791568fe74e44a4a173541deb7
diff --git a/core/dumpvar.mk b/core/dumpvar.mk
index 47ac9e2..92bf6af 100644
--- a/core/dumpvar.mk
+++ b/core/dumpvar.mk
@@ -98,6 +98,7 @@
 $(info   TARGET_BUILD_APPS=$(TARGET_BUILD_APPS))
 $(info   TARGET_ARCH=$(TARGET_ARCH))
 $(info   TARGET_ARCH_VARIANT=$(TARGET_ARCH_VARIANT))
+$(info   TARGET_CPU_VARIANT=$(TARGET_CPU_VARIANT))
 $(info   HOST_ARCH=$(HOST_ARCH))
 $(info   HOST_OS=$(HOST_OS))
 $(info   HOST_OS_EXTRA=$(HOST_OS_EXTRA))