ipn/store/awsstore: add "ts_omit_aws" build tag to reduce binary size

Drops tailscaled from 23M to 21M.

Change-Id: I731c542d03113ac94abb695e3c8fcacbc5542712
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

.github/workflows/linux.yml

@@ -28,6 +28,11 @@ jobs:
     - name: Basic build
       run: go build ./cmd/...
 
+    - name: Build variants
+      run: |
+        go install --tags=ts_include_cli ./cmd/tailscaled
+        go install --tags=ts_omit_aws ./cmd/tailscaled
+
     - name: Get QEMU
       run: |
         # The qemu in Ubuntu 20.04 (Focal) is too old; we need 5.x something

ipn/store/awsstore/store_aws.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build linux
-// +build linux
+//go:build linux && !ts_omit_aws
+// +build linux,!ts_omit_aws
 
 // Package awsstore contains an ipn.StateStore implementation using AWS SSM.
 package awsstore

ipn/store/awsstore/store_aws_stub.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !linux
-// +build !linux
+//go:build !linux || ts_omit_aws
+// +build !linux ts_omit_aws
 
 package awsstore
 
@@ -12,8 +12,9 @@ import (
 	"runtime"
 
 	"tailscale.com/ipn"
+	"tailscale.com/types/logger"
 )
 
-func NewStore(string) (ipn.StateStore, error) {
+func New(logger.Logf, string) (ipn.StateStore, error) {
 	return nil, fmt.Errorf("AWS store is not supported on %v", runtime.GOOS)
 }