Translate non-printing input characters using the codepage, don't assume

anything that doesn't print is "fine".

src/conio/sdl_con.c

@@ -827,8 +827,14 @@ static void sdl_video_event_thread(void *data)
 							break;
 						}
 					}
-					if (block_text || ev.key.keysym.sym < 0 || ev.key.keysym.sym > 128 || !isprint(ev.key.keysym.sym))
+					if (block_text || ev.key.keysym.sym < 0 || ev.key.keysym.sym > 128) {
 						sdl_add_key(sdl_get_char_code(ev.key.keysym.sym, ev.key.keysym.mod));
+					}
+					else if (!isprint(ev.key.keysym.sym)) {
+						uint8_t ch = cpchar_from_unicode_cpoint(getcodepage(), ev.key.keysym.sym, 0);
+						if (ch)
+							sdl_add_key(ch);
+					}
 					break;
 				case SDL_TEXTINPUT:
 					if (!block_text)