FILEIO: XFILE needs to be compiled with USE_LFILE in DOS.

Fixes commit 57f68bc612eb50583a9638c559cef573ca263a04.

The bug caused PJ to crash on startup when AA.CFG was missing.
FILEIO: add xferror, XFILE replacement for ferror.
FILEIO: convert BMP to XFILE.
FILEIO: convert GIF to XFILE.
FILEIO: convert PCX to XFILE.
FILEIO: convert RIF to XFILE.
FILEIO: convert TARGA to XFILE.