Defer hard timeout

Abort kresd on too long work on a single request.

lib/sigsafe.h

@@ -15,4 +15,4 @@
 ///   * %r takes (struct sockaddr *).
 KR_EXPORT
 int sigsafe_format(char *str, size_t size, const char *fmt, ...);
-#define sigsafe_format(...) sigsafe_format(__VA_ARGS__) // NOLINT(bugprone-signal-handler)
+#define sigsafe_format(...) sigsafe_format(__VA_ARGS__) // NOLINT, all calls are async-signal-safe