Cygwin: pipe: Introduce temporary query_hdl.

Cygwin: pipe: Introduce temporary query_hdl.

- The commit f79a4611 introduced query_hdl, which is the read pipe
  handle kept in the write pipe instance in order to determine if
  the pipe is ready to write in select().  This implementation has
  a potential risk that the write side fails to detect the closure
  of the read side if more than one writer exists and one of them
  is a non-cygwin process.

  With this patch, the strategy of commit f79a4611 is used only if
  the process is running as a service.  For a normal process,
  instead of keeping query_hdl in the write pipe instance, it is
  retrieved temporarily when select() is called.  Actually, we
  want to use tenporary query_hdl for all processes, however, it
  does not work for service processes due to OpenProcess()
  failure.