Old implementation was not thread safe, incorrectly copied file
descriptors to child process and was leaking parent pipe fd to child
process.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=51719Signed-off-by: Piotr Caban <piotr@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>