When the vndk is enabled (BOARD_VNDK_VERSION=current),
vendor libraries must only link against vendor variants
in the build system. This also means that they receive
restricted sets of headers and that automatic global
headers are restricted.
Test: build libqservice with BOARD_VNDK_VERSION=current
Bug: 69526027
Change-Id: Id98bf5e2ecc6f514f1d4dd9580d25027f36e0d86