feature/featuretags: add a catch-all "Debug" feature flag

Saves 168 KB.

Updates #12614

Change-Id: Iaab3ae3efc6ddc7da39629ef13e5ec44976952ba
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

feature/buildfeatures/feature_debug_disabled.go

@@ -0,0 +1,13 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Code generated by gen.go; DO NOT EDIT.
+
+//go:build ts_omit_debug
+
+package buildfeatures
+
+// HasDebug is whether the binary was built with support for modular feature "various debug support, for things that don't have or need their own more specific feature".
+// Specifically, it's whether the binary was NOT built with the "ts_omit_debug" build tag.
+// It's a const so it can be used for dead code elimination.
+const HasDebug = false

feature/buildfeatures/feature_debug_enabled.go

@@ -0,0 +1,13 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Code generated by gen.go; DO NOT EDIT.
+
+//go:build !ts_omit_debug
+
+package buildfeatures
+
+// HasDebug is whether the binary was built with support for modular feature "various debug support, for things that don't have or need their own more specific feature".
+// Specifically, it's whether the binary was NOT built with the "ts_omit_debug" build tag.
+// It's a const so it can be used for dead code elimination.
+const HasDebug = true

feature/featuretags/featuretags.go

@@ -97,6 +97,7 @@ var Features = map[FeatureTag]FeatureMeta{
 	"clientupdate":  {"ClientUpdate", "Client auto-update support", nil},
 	"completion":    {"Completion", "CLI shell completion", nil},
 	"dbus":          {"DBus", "Linux DBus support", nil},
+	"debug":         {"Debug", "various debug support, for things that don't have or need their own more specific feature", nil},
 	"debugeventbus": {"DebugEventBus", "eventbus debug support", nil},
 	"debugportmapper": {
 		Sym:  "DebugPortMapper",