Add small testsuite fixes for 4.11 kernels.

Add small testsuite fixes for 4.11 kernels.

* testsuite/buildok/twentyseven.stp: Avoid missing inlined function
  arguments by probing 'kernel.function("do_execve").call'.
* testsuite/buildok/thirtyone.stp: On 4.11 kernels, handle the vfs_stat()
  function being renamed to vfs_statx().
* testsuite/systemtap.pass1-4/buildok.exp: Add kfails for
  buildok/fortyfour.stp and buildok/map_probe_cond.stp if we don't have
  uprobes.
* testsuite/systemtap.pass1-4/buildok-interactive.exp: Ditto.