httpsrv: Some older versions of libmicrohttpd need stdint.h included first

httpsrv.c

@@ -9,6 +9,7 @@
 
 #include "config.h"
 
+#include <stdint.h>
 #include <sys/types.h>
 #include <sys/select.h>
 #include <sys/socket.h>