rust: Allow rust sysprop libraries to be installed.

These libraries should be installable, otherwise the dylib won't
be installed to the device leading to runtime linker errors.

Bug: 380116147
Test: m <library w/ sysprop_library dep>; ls $OUT/system/lib64
Change-Id: Ieeff24d9c2f3bfa79e5f63c89e780b394716257d