feature/featuretags, all: add ts_omit_acme to disable TLS cert support

I'd started to do this in the earlier ts_omit_server PR but
decided to split it into this separate PR.

Updates #17128

Change-Id: Ief8823a78d1f7bbb79e64a5cab30a7d0a5d6ff4b
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

build_dist.sh

@@ -41,7 +41,7 @@ while [ "$#" -gt 1 ]; do
 		fi
 		shift
 		ldflags="$ldflags -w -s"
-		tags="${tags:+$tags,},$($go run ./cmd/featuretags --min)"
+		tags="${tags:+$tags,},$(GOOS= GOARCH= $go run ./cmd/featuretags --min)"
 		;;
 	--box)
 		if [ ! -z "${TAGS:-}" ]; then