Use the more standard files xalloc.h' and xmalloc.c' instead of

Bison's `allocate.c' and `alloc.h'.  This patch was surprisingly
difficult and introduced a lot of core dump.  It turns out that
Bison used an implementation of `xmalloc' based on `calloc', and
at various places it does depend upon the initialization to 0.  I
have not tried to isolate the pertinent places, and all the former
calls to Bison's `xmalloc' are now using `XCALLOC'.  Someday,
someone should address this issue.
* src/allocate.c, src/alloc.h, m4/bison-decl.m4: Remove.
* lib/xmalloc.c, lib/xalloc.h, m4/malloc.m4, m4/realloc.m4: New
files.
Adjust dependencies.
* src/warshall.h: New file.
Propagate.

m4/bison-decl.m4

@@ -1,48 +0,0 @@
-dnl FIXME: This should be soon obsoleted by AC_CHECK_DECL.
-
-dnl See whether we need a declaration for a function.
-dnl BISON_NEED_DECLARATION(FUNCTION [, EXTRA-HEADER-FILES])
-AC_DEFUN(BISON_NEED_DECLARATION,
-[AC_MSG_CHECKING([whether $1 must be declared])
-AC_CACHE_VAL(bison_cv_decl_needed_$1,
-[AC_TRY_COMPILE([
-#include <stdio.h>
-#ifdef HAVE_STRING_H
-#include <string.h>
-#else
-#ifdef HAVE_STRINGS_H
-#include <strings.h>
-#endif
-#endif
-#ifdef HAVE_STDLIB_H
-#include <stdlib.h>
-#endif
-#ifdef HAVE_UNISTD_H
-#include <unistd.h>
-#endif
-#ifndef HAVE_RINDEX
-#define rindex strrchr
-#endif
-#ifndef HAVE_INDEX
-#define index strchr
-#endif
-$2],
-[char *(*pfn) = (char *(*)) $1],
-eval "bison_cv_decl_needed_$1=no", eval "bison_cv_decl_needed_$1=yes")])
-if eval "test \"`echo '$bison_cv_decl_needed_'$1`\" = yes"; then
-  AC_MSG_RESULT(yes)
-  bison_tr_decl=NEED_DECLARATION_`echo $1 | tr 'abcdefghijklmnopqrstuvwxyz' 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'`
-  AC_DEFINE_UNQUOTED($bison_tr_decl)
-else
-  AC_MSG_RESULT(no)
-fi
-])dnl
-
-dnl Check multiple functions to see whether each needs a declaration.
-dnl BISON_NEED_DECLARATIONS(FUNCTION... [, EXTRA-HEADER-FILES])
-AC_DEFUN(BISON_NEED_DECLARATIONS,
-[for ac_func in $1
-do
-BISON_NEED_DECLARATION($ac_func, $2)
-done
-])