os: drop special case for FreeBSD 10.4 in newFile
os: drop special case for FreeBSD 10.4 in newFile

Support for FreeBSD 10 will be dropped with Go 1.13, so revert the
workaround introduced in CL 157099.

Updates #29633
Updates #27619

Change-Id: I1a2e50d3f807a411389f3db07c0f4535a590da02
Reviewed-on: https://go-review.googlesource.com/c/go/+/165801
Run-TryBot: Tobias Klauser <0a68dd4915066ec5d3f81f75a828fee53dcc8822@gmail.com>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

nawawi/go,golang/go,CAFxX/go,golang/go,cloudflare/go,cloudflare/go,nawawi/go,cloudflare/go,nawawi/go,josharian/go,akutz/go,akutz/go,CAFxX/go,akutz/go,CAFxX/go,akutz/go,golang/go,josharian/go,nawawi/go,akutz/go,josharian/go,CAFxX/go,CAFxX/go,josharian/go,nawawi/go,cloudflare/go,golang/go,CAFxX/go,josharian/go,akutz/go,CAFxX/go,nawawi/go,golang/go,golang/go,cloudflare/go,CAFxX/go,cloudflare/go,josharian/go,golang/go,cloudflare/go,cloudflare/go,nawawi/go,josharian/go,golang/go,akutz/go,akutz/go,nawawi/go,josharian/go