openbsd: make test lib/std/std.zig pass

* According to OpenBSD's getdents docs indicate the buffer must be
  greater or or equal to the block size associated with the file and to
  refer to stat(2).
* Use S_BLKSIZE, which is 512, instead of @sizeOf(std.c.dirent), which is 280.
* Oddly the other BSDs are not this picky.
09f06082f0Michael Dusan committed on 12/30/2025, 2:40:02 AMparent1ea2d56
3 files changedLine totals unavailable