Fixed "homremoval" cvar disregards non-green resolutions

[Lactozilla]

Line 777 of v_video.c checks for BASEVIDWIDTH and BASEVIDHEIGHT, rather than vid.width and vid.height:

if (x == 0 && y == 0 && w == BASEVIDWIDTH && h == BASEVIDHEIGHT)
{ // Clear the entire screen, from dest to deststop. Yes, this really works.
	memset(screens[0], (UINT8)(c&255), vid.width * vid.height * vid.bpp);
	return;
}

It conflicts with the actual homremoval code:

V_DrawFill(0, 0, vid.width, vid.height, 31);

 

[Monster Iestyn]

I have made a fix for this bug, the merge request for which is here: https://git.magicalgirl.moe/STJr/SRB2/merge_requests/273