This allows to perform a fcntl syscall with the F_PREALLOCATE command.
See man fcntl(2) on macOS for details.
Change-Id: I21f95b91269513064859425ab7adc42a73d6adb5
Reviewed-on: https://go-review.googlesource.com/c/sys/+/255917
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>