* util/misc.c: Include config.h.
[!HAVE_MEMALIGN]: Do not include malloc.h.
(grub_memalign): Use posix_memalign, if present. Then, use
memalign, if present. Otherwise, emit an error.
* util/grub-emu.c: Do not include malloc.h.
* include/grub/util/misc.h: Include unistd.h. This is required for
FreeBSD, because off_t is defined in unistd.h. Reported by Harley
D. Eades III <hde@foobar-qux.org>.
* configure.ac (AC_GNU_SOURCE): Added.
(AC_CHECK_FUNCS): Check posix_memalign and memalign for the host
type.