Added an option to "process detach" to keep the process stopped, if the process plugin (or in the
case of ProcessGDBRemote the stub we are talking to) know how to do that.

rdar://problem/13680832


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@180831 91177308-0d34-0410-b5e6-96231b3b80d8