Added debugserver/llgs protocol test for output and clean exit.

Tests for $vCont;c program start, $O output and $W status code.
@llgs_test variant currently marked as expected fail.



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@207492 91177308-0d34-0410-b5e6-96231b3b80d8