NativeBridge: add "linked namespace" semantic corresponding to linker

For dynamic linking perspective, semantics of NativeBridge needs to
align with dynamic linker. This patch adds "linked namespace" semantic
which shares some libraries from one namespace to another.

Test: make test-art-host-run-test-115-native-bridge
Change-Id: I71ce1dde19d61363d5eb9731fd4795a8c315b3a0