Revert some of the previous change; intead, fix the HAVE_GETCWD_NULL code to behave more like the !HAVE_GETCWD_NULL code used to. Include "xalloc.h". (xgetcwd): Do not return NULL when memory is exhausted; instead, invoke xalloc_die.

#ifndef PARAMS
# if defined PROTOTYPES || (defined __STDC__ && __STDC__)
#  define PARAMS(Args) Args
# else
#  define PARAMS(Args) ()
# endif
#endif

int
  memcasecmp PARAMS ((const void *vs1, const void *vs2, size_t n));