Determine product partition path on build time

Path of product partitoin can be set as /product or /system/product
whether generate extra product partition or not.
Substitute %PRODUCT% to relevant path to know linker which path should
search and permit.

Bug: 110286945
Test: m -j # Check /system/etc/ld.config.$(PLATFORM_VNDK_VERSION).txt
Change-Id: I6ca177d0c9c5af00ad821879fece40848331fc8d