Make ext2fs_init() call ufs_init(). it was doing the init by itself,
testing for extern done != 0. This bug was hidden by the fact that
ext2fs_init() is called before ffs_init().
Only assembly version for i386 bswap16 and bswap32 for now (bswap64 uses
bswap32). Contribution of assembly versions of these are welcome.
Add byte-swapping of ext2fs metadata for big-endian systems.
Tested on i386 and sparc.