Allow layoutlib to access core-libart

layoutlib is one of the existing direct users of core-libart,
but was not listed in visibility because it was in Make.  Add
it to visiblility to allow converting it to Soong.

Bug: 122333007
Test: m temp_layoutlib
Change-Id: I73d0c091e26e0d622cbe1459922f35d875bc14b7
1 file changed