duke3d: allow playing with unofficial data files

I'd overlooked this code path earlier. In the case of an unknown GRP, the
game would poll SDL for keyboard input, which it never received. Remove
that, and just warn the user instead.

Change-Id: Ibbabc0f8d43cb1276ed2fcfc3c6138517582e936

apps/plugins/sdl/progs/duke3d/Game/src/game.c

@@ -8166,6 +8166,7 @@ int main(int argc,char  **argv)
                 for(i=0; i<MAX_KNOWN_GRP; i++)
                         printf("%s -> CRC32=%X  Size=%d bytes\n", crc32lookup[i].name, crc32lookup[i].crc32, crc32lookup[i].size);
 
+#if 0
                 printf( "\nYou should try to get one of these GRP only as a base GRP\n"
                                 "Do you want to continue anyway? (Y/N): ");
                 do
@@ -8175,6 +8176,8 @@ int main(int argc,char  **argv)
 
                 if(kbdKey == 'n')
                         Error(EXIT_SUCCESS,"");
+#endif
+                rb->splashf(HZ, "WARNING: Your GRP is not a well-known version. Continue at your own risk!");
         }
 
         // computing exe crc