Clean up vid access a little

Things are still a mess, but a proper cleanup will be a lot of work and
will, really, involve properly splitting quake-specific code* out from
the rest of the renderer.

* data loading and format specific stuff

include/r_screen.h

@@ -64,8 +64,6 @@ extern struct qpic_s *scr_turtle;
 extern int         clearconsole;
 extern int         clearnotify;
 
-extern viddef_t    vid;						// global video state
-
 extern vrect_t    *pconupdate;
 extern vrect_t     scr_vrect;
 

libs/video/renderer/r_screen.c

@@ -104,8 +104,6 @@ qpic_t     *scr_turtle;
 
 int         clearconsole;
 
-viddef_t    vid;						// global video state
-
 vrect_t    *pconupdate;
 vrect_t     scr_vrect;
 
@@ -365,6 +363,5 @@ SCR_Init (void)
 	scr_ram = vr_funcs->Draw_PicFromWad ("ram");
 	scr_turtle = vr_funcs->Draw_PicFromWad ("turtle");
 
-	vid = *vr_data.vid;	// cache
 	scr_initialized = true;
 }

libs/video/renderer/vid_common.c

@@ -34,6 +34,8 @@
 #include "mod_internal.h"
 #include "r_internal.h"
 
+viddef_t    vid;					// global video state
+
 vid_render_data_t vid_render_data = {
 	&vid, &r_refdef, &scr_vrect,
 	0, 0, 0,