FIX: build when using X11

[ismagilli]

The problem occurs when trying to build a game using X11.
There is such a line in the X11/X.h file:

/*****************************************************************
* RESERVED RESOURCE AND CONSTANT DEFINITIONS
*****************************************************************/
...
#define AnyKey     0L /* special Key Code, passed to GrabKey */

At the same time, in the doomretro code, there is the following enum in the p_spec.h file:

// define names for the locked door Kind field of the general ceiling
enum
{
    AnyKey,
    ...
};

Include chain:

i_video.c:37: #include <X11/Xlib.h>
    /usr/include/X11/Xlib.h:44: #include <X11/X.h>
i_video.c:55: #include "m_config.h"
    m_config.h:39: #include "p_local.h"
    p_local.h:341: #include "p_spec.h"

Therefore, a problem occurs when compiling i_video.c:

cc -O2 -fsigned-char -g `sdl2-config --cflags` -DX11 -c i_video.c -o i_video.o
In file included from /usr/include/X11/Xlib.h:44,
                from i_video.c:37:
p_spec.h:822:5: error: expected identifier before numeric constant
822 |     AnyKey,
    |     ^~~~~~
make: *** [Makefile:55: i_video.o] Error 1

It is reproduced on many popular linux distributions.

One of the possible ways is to reproduce:

1. Use ubuntu docker container: docker run -it ubuntu bash;
2. Update list of available packages: # apt update;
3. Upgrade the system: # apt upgrade -y;
4. Install required packages: # apt install -y git gcc make libsdl2-dev libsdl2-image-dev libsdl2-mixer-dev;
5. Clone doomretro repo: $ git clone https://github.com/bradharding/doomretro;
6. Enter source directory: $ cd doomretro/src;
7. Build i_video.c: $ make i_video.o.

Commands 2-4 and 5-7 can be combined into 2 commands:

1. # apt update && apt upgrade -y && apt install -y git gcc make libsdl2-dev libsdl2-image-dev libsdl2-mixer-dev;
2. $ git clone https://github.com/bradharding/doomretro && cd doomretro/src && make i_video.o.

[bradharding]

Thank you!