Patch to optionally disable overlapped pipes

[Christopher Faylor]

On Tue, Dec 24, 2013 at 11:01:21PM -0000, James Johnston wrote:
>Hi,
>
>As I have recently mentioned on the main Cygwin mailing list, Cygwin by
>default creates FILE_FLAG_OVERLAPPED named pipes for the standard file
>handles (stdin/stdout/stderr).  These overlapped pipes require all programs
>using ReadFile/WriteFile to use overlapped I/O when using the pipes.

Thanks for the patch but Cygwin has been using overlapped I/O with pipes
for many years.  They are a requirement for proper operation with
signals.  We try to be very sparing when adding new options and we're
not going to add an option to make things work less reliably.

cgf