build/log: add log types + NewSubLogger

build/log_nolog.go

@@ -0,0 +1,11 @@
+// +build nolog
+
+package build
+
+// LoggingType is a log type that writes no logs.
+const LoggingType = LogTypeNone
+
+// Write is a noop.
+func (w *LogWriter) Write(b []byte) (int, error) {
+	return len(b), nil
+}