Add support for the JFS filesystem.
* fs/jfs.c: New file.
* include/grub/fs.h (grub_jfs_init): New prototype.
(grub_jfs_fini): New prototype.
* conf/i386-pc.rmk (grub_setup_SOURCES): Add fs/jfs.c.
(grub_emu_SOURCES): Likewise.
(pkgdata_MODULES): Add jfs.mod.
(jfs_mod_SOURCES): New variable.
(jfs_mod_CFLAGS): Likewise.
* conf/powerpc-ieee1275.rmk (grub_emu_SOURCES): Add fs.jfs.c.
(grubof_SOURCES): Likewise.
* util/grub-emu.c (main): Initialize and deinitialize JFS support.
* fs/fat.c (grub_fat_find_dir): Convert the filename little
endian to the host endian.
(grub_fat_utf16_to_utf8): Move function from there...
* kern/misc.c (grub_utf16_to_utf8): ...to here. Do not convert
the endianess of the source string anymore.
* include/grub/misc.h (grub_utf16_to_utf8): New prototype.
