Reason for revert: Fallback path is still required on Solaris.
For #45964
For #59359
Change-Id: I4b8c8af77ee987cad6617221793b90c9a8829c3e
Reviewed-on: https://go-review.googlesource.com/c/go/+/501276
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org> Reviewed-by: Ian Lance Taylor <iant@google.com>