Adding a mechanism to conditionally exclude some shared library
dependencies when a lib is built for vendors.
Without this, some libraries cannot be earily marked as vendor_available
if they are depending on shared libs can shouldn't be marked as
vendor_available.
By using exclude_shared_libs with exclude_srcs (or __ANDROID_VNDK__
macro), we can eliminate the unnecessary dependency for vendors.
Bug: 62471389
Test: build
Change-Id: If94277b45c3769223cea371d0028e75277640356