Do not dedupe libprotobuf-cpp variants

The vendor variants of libprotobuf-cpp have their version numbers
included in their names, so the SONAME field is different.  Whitelist
the 'lite' and 'full' versions to have different core and vendor
variants.

Test: Build a device with TARGET_VNDK_USE_CORE_VARIANT set.
Change-Id: I9880a5d7172a9f35f304af8e7dcababdcbc2ca23