civetweb.c: fix format string from %d to %u

[src/civetweb.c:366]: (warning) %d in format string (no. 4) requires
 'int' but the argument type is 'unsigned int'.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>

src/civetweb.c

@@ -363,7 +363,7 @@ static void DEBUG_TRACE_FUNC(const char *func, unsigned line, const char *fmt, .
 
   va_list args;
   flockfile(stdout);
-  printf("*** %lu.%p.%s.%d: ",
+  printf("*** %lu.%p.%s.%u: ",
          (unsigned long) time(NULL), (void *) pthread_self(),
          func, line);
   va_start(args, fmt);