cmd/dist: add support for freebsd/arm64

Updates #24715

Change-Id: I110a10a5d5ed4a471f67f35cbcdcbea296c5dcaf
Reviewed-on: https://go-review.googlesource.com/c/go/+/198542
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/dist/build.go

@@ -1485,6 +1485,7 @@ var cgoEnabled = map[string]bool{
 	"freebsd/386":     true,
 	"freebsd/amd64":   true,
 	"freebsd/arm":     true,
+	"freebsd/arm64":   false,
 	"illumos/amd64":   true,
 	"linux/386":       true,
 	"linux/amd64":     true,