Process::StopForDetachOrDestroy should actually return an error if it can't stop the process.
Process::StopForDetachOrDestroy should actually return an error if it can't stop the
process.

<rdar://problem/26990309>


git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@274032 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb