Initial underlying code support for more than 2 video cards

src/unix/unix.c

@@ -1168,7 +1168,7 @@ monitor_thread(void *param)
 #endif
 }
 
-extern int gfxcard[2];
+extern int gfxcard[GFXCARD_MAX];
 int
 main(int argc, char **argv)
 {
@@ -1186,7 +1186,8 @@ main(int argc, char **argv)
         return 6;
     }
 
-    gfxcard[1]  = 0;
+    for (uint8_t i = 1; i < GFXCARD_MAX; i++)
+        gfxcard[i]  = 0;
     eventthread = SDL_ThreadID();
     blitmtx     = SDL_CreateMutex();
     if (!blitmtx) {