Test case to verify that lldb falls back to p/P if g is unsupported

and that lldb uses the expedited register values in the ? packet
aka stop packet (T11 etc) and does not re-fetch them with the p packet.

This test is currently failing from the "[lldb-server] Add setting to
force 'g' packet use" commit; I'm marking it as @expectedFailureAll
until we can get this fixed.