log: add log.use_stdout(), use it to silence the transition note for the most commonly used V tools/examples (#23642)

cmd/tools/fast/fast.v

@@ -41,6 +41,7 @@ fn lexec(cmd string) string {
 
 fn main() {
 	// ensure all log messages will be visible to the observers, even if the program panics
+	log.use_stdout()
 	log.set_always_flush(true)
 
 	total_sw := time.new_stopwatch()

cmd/tools/gen_vc.v

@@ -97,6 +97,7 @@ struct FlagOptions {
 }
 
 fn main() {
+	log.use_stdout()
 	mut fp := flag.new_flag_parser(os.args.clone())
 	fp.application(app_name)
 	fp.version(app_version)

cmd/tools/vcover/main.v

@@ -148,6 +148,7 @@ fn normalize_path(path string) string {
 }
 
 fn main() {
+	log.use_stdout()
 	mut ctx := Context{}
 	ctx.working_folder = normalize_path(os.real_path(os.getwd()))
 	mut fp := flag.new_flag_parser(os.args#[1..])

cmd/tools/vdownload.v

@@ -23,9 +23,7 @@ mut:
 const vexe = os.real_path(os.getenv_opt('VEXE') or { @VEXE })
 
 fn main() {
-	mut l := log.ThreadSafeLog{}
-	l.set_output_stream(os.stdout())
-	log.set_logger(l)
+	log.use_stdout()
 	mut ctx := Context{}
 	mut fp := flag.new_flag_parser(os.args#[1..])
 	fp.application(os.file_name(os.executable()))

cmd/tools/vretry_test.v

@@ -22,6 +22,7 @@ fn run(cmd string) os.Result {
 }
 
 fn test_retry() {
+	log.use_stdout()
 	log.warn('start...')
 	defer {
 		log.warn('... done')

cmd/tools/vshould-compile-all.v

@@ -4,6 +4,7 @@ import log
 const should_clean = os.args.contains('-c')
 
 fn main() {
+	log.use_stdout()
 	mut files := []string{}
 	args := os.args#[2..].filter(it != '-c')
 	for a in args {