cmd/dist: require Go 1.17 for building Go

cmd/dist: require Go 1.17 for building Go

This makes builds using earlier Go bootstrap versions fail pretty clearly:

% GOROOT_BOOTSTRAP=$HOME/sdk/go1.16 ./make.bash
Building Go cmd/dist using /Users/rsc/sdk/go1.16. (go1.16 darwin/amd64)
found packages main (build.go) and building_Go_requires_Go_1_17_or_later (notgo117.go) in /Users/rsc/go/src/cmd/dist
%

All the builders have Go 1.17 or later for bootstrap now except
for the android corellium builders, which still need updating (#54246).
We are accepting breakage on those for now.

Fixes #44505.

Change-Id: I12a67f42f61dba43a331cee0a150194d3e42c044
Reviewed-on: https://go-review.googlesource.com/c/go/+/420902
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Russ Cox <rsc@golang.org>