* conf/common.rmk (pkglib_MODULES): Add bufio.mod.
(bufio_mod_SOURCES): New macro.
(bufio_mod_CFLAGS): Likewise.
(bufio_mod_LDFLAGS): Likewise.
* include/grub/bufio.h: New file.
* io/bufio.c: Likewise.
* video/png.c: Replace <grub/file.h> with <grub/bufio.h>.
(grub_video_reader_png): Use grub_buffile_open to open file.
* video/jpeg.c: Replace <grub/file.h> with <grub/bufio.h>.
(grub_video_reader_jpeg): Use grub_buffile_open to open file.
* video/tga.c: Replace <grub/file.h> with <grub/bufio.h>.
(grub_video_reader_tga): Use grub_buffile_open to open file.
* font/manager.c: Include <grub/bufio.h>.
(add_font): Use grub_buffile_open to open file.
