message: Fix windows/mac builds broken by r333182.
  I should've known that something was wrong when only one of my plugins
  was prefixed by the lldb_private namespace.
diff: #if defined(__APPLE__)
  #include "Plugins/ObjectFile/Mach-O/ObjectFileMachO.h"
  -using HostObjectFile = lldb_private::ObjectFileMachO;
  +using HostObjectFile = ObjectFileMachO;
  #elif defined(_WIN32)
  #include "Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.h"
  -using HostObjectFile = lldb_private::ObjectFilePECOFF;
  +using HostObjectFile = ObjectFilePECOFF;
  #else
  #include "Plugins/ObjectFile/ELF/ObjectFileELF.h"
  using HostObjectFile = ObjectFileELF;
  