Fix byte issue, other warnings and deprecation

[d-a-v]

These changes are backward compatible with older cores.
They will:

• remove warnings
• honor deprecation (esp8266 Arduino core v3+)
• related: weird error in arduino.h on makeWord () with core 3.0.0 esp8266/Arduino#8089 (c++17)

[gmag11]

Why do you need this?

[d-a-v]

This is to avoid a compiler warning indicating that a parameter is unused.
It is visible when full & verbose logs are enabled in the arduino IDE preferences panel.
This idiom explicitly tells to the compiler to stay silent because we already know about that fact and that's on purpose.

Here's the warning:

libraries/NtpClient/src/NTPClientLib.cpp: In static member function 'static void NTPClient::s_dnsFound(const char*, const ip_addr_t*, void*)':
libraries/NtpClient/src/NTPClientLib.cpp:201:41: warning: unused parameter 'name' [-Wunused-parameter]
  201 | void NTPClient::s_dnsFound (const char *name, const ip_addr_t *ipaddr, void *callback_arg) {
      |                             ~~~~~~~~~~~~^~~~

Thanks for reviewing !

[bill-orange]

Incorporating this pull request manually, I can compile with the ESP8266 3.0.1 board manager just fine. It also appears compatible with 2.7.4