[PATCH 2/2] msvcrt: Rewrite _popen function.

[Piotr Caban]

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=51719
Signed-off-by: Piotr Caban <piotr(a)codeweavers.com>
---
  dlls/msvcrt/process.c    | 217 ++++++++++++++++++++++-----------------
  dlls/msvcrt/tests/misc.c |  50 +++++++--
  2 files changed, 166 insertions(+), 101 deletions(-)