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.

src/main.c

@@ -32,6 +32,7 @@
 #include "nullable.h"
 #include "print.h"
 #include "LR0.h"
+#include "conflicts.h"
 
 /* The name this program was run with, for messages.  */
 char *program_name;