Remove pipe close before exec.
Remove pipe close before exec.

Pipe close before exec is not necessary as os.Pipe() is calling pipe2
with O_CLOEXEC option.

Signed-off-by: Marco Vedovati <7ad294ca8ed51ab6f7b6cc42294ec572c85df1f5@suse.com>

justincormack/runc,mYmNeo/runc,mheon/runc,mheon/runc,dqminh/runc,mikebrow/runc,dqminh/runc,kolyshkin/runc,dqminh/runc,mYmNeo/runc,justincormack/runc,estesp/runc,adrianreber/runc,xiaochenshen/runc,opencontainers/runc,mikebrow/runc,estesp/runc,mheon/runc,opencontainers/runc,rhatdan/runc,mYmNeo/runc,dqminh/runc,adrianreber/runc,adrianreber/runc,xiaochenshen/runc,kolyshkin/runc,opencontainers/runc,rhatdan/runc,kolyshkin/runc,estesp/runc,xiaochenshen/runc,rhatdan/runc,rhatdan/runc,opencontainers/runc,justincormack/runc,mikebrow/runc,kolyshkin/runc