Modernize header macros for C23 compatibility

Modernize header macros for C23 compatibility

Replace old-style (int (*)()) and (char *(*)()) casts with proper typed
prototypes (i2d_of_void *, d2i_of_void *, void *(*)(void)) to comply
with stricter C23 function pointer rules.

Fixes #27938

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/29048)