Include hard-locale.h, xmemcoll.h.

Include hard-locale.h, xmemcoll.h.
(hard_LC_COLLATE): New var.
(different): Args are now char *, not const char *.
Use xmemcoll instead of memcmp to compare lines, so that
LC_COLLATE has effect.  However, use memcmp if it is an
easy locale.
(check_file): Do not include newline in comparison, so that
xmemcoll has a byte to stomp on temporarily.
(main): Set hard_LC_COLLATE.