Bug fix for ``MakeRuleCmd.create_relative_symbolic_link()``.
Bug fix for ``MakeRuleCmd.create_relative_symbolic_link()``.

create_relative_symbolic_link(out, '/usr/lib64/libz3.so',
'/usr/lib/python3.5/site-package/libz3.so') would create an incorrect relative
path because it would consider ``/usr/lib`` to a be a path prefix of
``/usr/lib64``.

seahorn/z3,mschlaipfer/z3,kyledewey/z3,kyledewey/z3,kyledewey/z3,kyledewey/z3,mschlaipfer/z3,seahorn/z3,seahorn/z3,seahorn/z3,mschlaipfer/z3,kyledewey/z3,mschlaipfer/z3,seahorn/z3,kyledewey/z3,mschlaipfer/z3,mschlaipfer/z3,seahorn/z3