minor optimization in puts: use inline putc_unlocked macro for newline

src/stdio/puts.c

@@ -4,7 +4,7 @@ int puts(const char *s)
 {
 	int r;
 	FLOCK(stdout);
-	r = -(fputs(s, stdout) < 0 || putchar('\n') < 0);
+	r = -(fputs(s, stdout) < 0 || putc_unlocked('\n', stdout) < 0);
 	FUNLOCK(stdout);
 	return r;
 }