Don't check VNDK lib list for PDK builds

Some libs, such as libandroid_net.so and some other Renderscript related
ones, can't be built in PDK due to missing frameworks/base.

Bug: 118634643
Test: build PDK; build doesn't break due to missing VNDK libs

Change-Id: Ic2bf657d796c2044c3b8f49b2963ca84760d54d1