os: use a lower file count for TestOpenFileLimit on openbsd
OpenBSD has a default soft limit of 512 and hard limit of 1024 - as such,
attempting to open 1200 files is always going to fail unless the defaults
have been changed. On this platform use 768 instead such that it passes
without requiring customisation.
Fixes #51713
Change-Id: I7679c8fd73d4b263145129e9308afdb29d67bb54
Reviewed-on: https://go-review.googlesource.com/c/go/+/401594 Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com> Reviewed-by: 谢致邦 <xiezhibang@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org> Reviewed-by: Peter Weinberger <pjw@google.com>