Bug#1039439: berusky: FTBFS with libsdl1.2-compat-dev: did you forget to '#include <cstddef>'?

[Simon McVittie]

Source: berusky
Version: 1.7.2-2
Severity: important
Tags: ftbfs trixie sid

I tried recompiling berusky with libsdl1.2-compat-dev instead of
libsdl1.2-dev, in preparation for having src:sdl12-compat take over the
libsdl1.2-dev package name.

It fails to compile with:

> In file included from stack.h:31,
>                  from level_game.h:32,
>                  from berusky.h:131:
> level_game.cpp: In constructor 'level_generic::level_generic(ITEM_REPOSITORY*)':
> level_game.cpp:107:29: error: expected primary-expression before ',' token
>   107 |   assert(offsetof(LEVEL_DISK, signum) == 0);
>       |                             ^
> level_game.cpp:107:31: error: 'signum' was not declared in this scope; did you mean 'signed'?
>   107 |   assert(offsetof(LEVEL_DISK, signum) == 0);
>       |                               ^~~~~~
> level_game.cpp:107:10: error: 'offsetof' was not declared in this scope
>   107 |   assert(offsetof(LEVEL_DISK, signum) == 0);
>       |          ^~~~~~~~
> level_game.cpp:35:1: note: 'offsetof' is defined in header '<cstddef>'; did you forget to '#include <cstddef>'?
>    34 | #include "berusky.h"
>   +++ |+#include <cstddef>
>    35 | 

Adding #include <cstddef> according to the compiler's hint fixes the FTBFS.

I'll ask sdl12-compat upstream to add <stddef.h> to the sdl12-compat
headers, but please fix this in berusky anyway, because <cstddef> is
preferred for C++ code (and SDL is C code).

Thanks,
    smcv