LibCore: Use void* instead of FlatPtr for ioctl() arg on Haiku

Author: https://github.com/ghost
Commit: 1e25ab956c
Pull-request: https://github.com/SerenityOS/serenity/pull/20808
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/Hendiadyoin1
Reviewed-by: https://github.com/diversys

Userland/Libraries/LibCore/System.cpp

@@ -709,7 +709,11 @@ ErrorOr<void> ioctl(int fd, unsigned request, ...)
 {
     va_list ap;
     va_start(ap, request);
+#ifdef AK_OS_HAIKU
+    void* arg = va_arg(ap, void*);
+#else
     FlatPtr arg = va_arg(ap, FlatPtr);
+#endif
     va_end(ap);
     if (::ioctl(fd, request, arg) < 0)
         return Error::from_syscall("ioctl"sv, -errno);