Don't have both lldb and debugserver call waitpid on the target process.  This sets up a race condition,
and if lldb wins, then debugserver won't get the correct error status to lldb.

<rdar://problem/16030008>


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@201744 91177308-0d34-0410-b5e6-96231b3b80d8