Define PRODUCT_PRODUCT_VNDK_VERSION

PRODUCT_PRODUCT_VNDK_VERSION sets the VNDK version for product
partition. It may have "current" to use the PLATFORM_VNDK_VERSION.
If PRODUCT_PRODUCT_VNDK_VERSION is set, the native modules in product
partition are enforced to use VNDK's only from the system partition
as BOARD_VNDK_VERSION did to vendor partition.

Bug: 144534640
Test: build
Change-Id: I7ea148f0f8b7e44be7810adcacb30702d66831f1