Warnings with recent compilers clang 19

[shikokuchuo]

Describe the bug

Recent updates to compiler versions unearth the following warnings:

1. http_server.c
   warning: 'sprintf' is deprecated: This function is provided for compatibility reasons only. Due to security concerns inherent in the design of sprintf(3), it is highly recommended that you use snprintf(3) instead. [-Wdeprecated-declarations]

2. aio.c
   runtime error: call to function nni_aio_free through pointer to incorrect function type 'void (*)(void *)'
   UndefinedBehaviorSanitizer: undefined-behavior

Solution

(1) You've already fixed in main, would be great to port this to stable.
(2) The cast of nni_aio_free() to type nni_cb is technically UB here: https://github.com/nanomsg/nng/blob/main/src/core/aio.c#L77

I will provide a PR for both of the above.

** Environment Details **

• NNG version 1.10.1
• Operating system and version: Ubuntu 22
• Compiler and language used: clang 19.1.7 with ASAN/UBSAN
• Static library