Replace `#ifdef BSD` (which requires including `<sys/param.h>` first) with explicit checks for `__FreeBSD__`, `__NetBSD__`, `__OpenBSD__` and `__DragonFly__`, matching how these BSDs are already enumerated elsewhere in the codebase (OS name strings, thread id helpers, etc.).
This also avoids leaking the `sys/param.h` requirement through public headers (`TracySysTime.hpp`, `TracyCallstack.h`), where consumers would otherwise need it to correctly see `TRACY_HAS_SYSTIME` / `TRACY_HAS_CALLSTACK`.
`libbacktrace/config.h` is left as-is — it's third-party and only included from .c files where the `BSD` macro can still be picked up locally.
Note: for `setsockopt( m_sock, IPPROTO_IPV6, IPV6_V6ONLY, (const char*)&val, sizeof( val ) );` I added `__APPLE__` too since this was the only place where it was not checked explicitely.
