2010-10-05  Szymon Janc <szymon@janc.net.pl>

	Make enable of disk cache statistics code configurable.

	* configure.ac: --enable-cache-stats added.
	* config.h.in (DISK_CACHE_STATS): New define.
	* grub-core/Makefile.core.def (cacheinfo): New command.
	* include/grub/disk.h(grub_disk_cache_get_performance): New function.
	* grub-core/commands/cacheinfo.c: New file.
	* grub-core/commands/minicmd.c (grub_rescue_cmd_info): Updated and
	moved to cacheinfo.c.
	* grub-core/kern/disk.c: Use DISK_CACHE_STATS to disable disk cache
	debug code.
	* include/grub/disk.h: Likewise.