runtime: overwrite startupRand instead of clearing it
AT_RANDOM is unfortunately used by libc before we run (so make sure it's
not cleared) but also is available to cgo programs after we did. It
would be unfortunate if a cgo program assumed it could use AT_RANDOM but
instead found all zeroes there.
Change-Id: I82eff34d8cf5a499b439052b7827b8ef7cabc21d
Reviewed-on: https://go-review.googlesource.com/c/go/+/608437 Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Daniel McCarney <daniel@binaryparadox.net>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Roland Shoemaker <roland@golang.org>