Make the rs namespace visible

This allows us to dlopen libRS_internal.so directly from the rs
namespace, not from the sphal namespace.

Bug: 64747884
Test: VtsHalRenderscriptV1_0TargetTest successful on the device built
with BOARD_VNDK_VERSION=current and [system] namespace config is applied
to /data/nativetest[64]/* processes.

Change-Id: I0b441791e395798e80a84592ca01e771bb1c201a