[dev.typeparams] runtime: use internal/abi.FuncPCABI0 for syscall wrappers on OpenBSD

[dev.typeparams] runtime: use internal/abi.FuncPCABI0 for syscall wrappers on OpenBSD

Same as CL 313230, for OpenBSD.

Change-Id: I56f4a8a368e1a17615a01db4e2b6c53e4ed263bd
Reviewed-on: https://go-review.googlesource.com/c/go/+/320889
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>