fix language code extraction

Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@2977

src/dos/dos_keyboard_layout.cpp

@@ -221,6 +221,7 @@ static Bit32u read_kcl_data(Bit8u * kcl_data, Bit32u kcl_data_size, const char*
 				// language ID found, return position
 				return cur_pos;
 			}
+			dpos+=2;
 		}
 		dpos=cur_pos+3+len;
 	}