diff -ur diffutils-2.8.7.original/m4/c-stack.m4 diffutils-2.8.7/m4/c-stack.m4
--- diffutils-2.8.7.original/m4/c-stack.m4	2004-03-07 17:51:10.000000000 -0600
+++ diffutils-2.8.7/m4/c-stack.m4	2010-02-13 14:30:38.319599733 -0600
@@ -19,142 +19,6 @@
 
 # Written by Paul Eggert.
 
-AC_DEFUN([AC_SYS_XSI_STACK_OVERFLOW_HEURISTIC],
-  [# for STACK_DIRECTION
-   AC_REQUIRE([AC_FUNC_ALLOCA])
-   AC_CHECK_FUNCS(setrlimit)
-
-   AC_CACHE_CHECK([for working C stack overflow detection],
-     ac_cv_sys_xsi_stack_overflow_heuristic,
-     [AC_TRY_RUN(
-	[
-	 #include <unistd.h>
-	 #include <signal.h>
-	 #include <ucontext.h>
-	 #if HAVE_SETRLIMIT
-	 # include <sys/types.h>
-	 # include <sys/time.h>
-	 # include <sys/resource.h>
-	 #endif
-
-	 static union
-	 {
-	   char buffer[SIGSTKSZ];
-	   long double ld;
-	   long u;
-	   void *p;
-	 } alternate_signal_stack;
-
-	 #if STACK_DIRECTION
-	 # define find_stack_direction(ptr) STACK_DIRECTION
-	 #else
-	 static int
-	 find_stack_direction (char const *addr)
-	 {
-	   char dummy;
-	   return (! addr ? find_stack_direction (&dummy)
-		   : addr < &dummy ? 1 : -1);
-	 }
-	 #endif
-
-	 static void
-	 segv_handler (int signo, siginfo_t *info, void *context)
-	 {
-	   if (0 < info->si_code)
-	     {
-	       ucontext_t const *user_context = context;
-	       char const *stack_min = user_context->uc_stack.ss_sp;
-	       size_t stack_size = user_context->uc_stack.ss_size;
-	       char const *faulting_address = info->si_addr;
-	       size_t s = faulting_address - stack_min;
-	       size_t page_size = sysconf (_SC_PAGESIZE);
-	       if (find_stack_direction (0) < 0)
-		 s += page_size;
-	       if (s < stack_size + page_size)
-		 _exit (0);
-	     }
-
-	   _exit (1);
-	 }
-
-	 static int
-	 c_stack_action (void)
-	 {
-	   stack_t st;
-	   struct sigaction act;
-	   int r;
-
-	   st.ss_flags = 0;
-	   st.ss_sp = alternate_signal_stack.buffer;
-	   st.ss_size = sizeof alternate_signal_stack.buffer;
-	   r = sigaltstack (&st, 0);
-	   if (r != 0)
-	     return r;
-
-	   sigemptyset (&act.sa_mask);
-	   act.sa_flags = SA_NODEFER | SA_ONSTACK | SA_RESETHAND | SA_SIGINFO;
-	   act.sa_sigaction = segv_handler;
-	   return sigaction (SIGSEGV, &act, 0);
-	 }
-
-	 static int
-	 recurse (char *p)
-	 {
-	   char array[500];
-	   array[0] = 1;
-	   return *p + recurse (array);
-	 }
-
-	 int
-	 main (void)
-	 {
-	   #if HAVE_SETRLIMIT && defined RLIMIT_STACK
-	   /* Before starting the endless recursion, try to be friendly
-	      to the user's machine.  On some Linux 2.2.x systems, there
-	      is no stack limit for user processes at all.  We don't want
-	      to kill such systems.  */
-	   struct rlimit rl;
-	   rl.rlim_cur = rl.rlim_max = 0x100000; /* 1 MB */
-	   setrlimit (RLIMIT_STACK, &rl);
-	   #endif
-
-	   c_stack_action ();
-	   return recurse ("\1");
-	 }
-	],
-	[ac_cv_sys_xsi_stack_overflow_heuristic=yes],
-	[ac_cv_sys_xsi_stack_overflow_heuristic=no],
-	[ac_cv_sys_xsi_stack_overflow_heuristic=cross-compiling])])
-
-   if test $ac_cv_sys_xsi_stack_overflow_heuristic = yes; then
-     AC_DEFINE(HAVE_XSI_STACK_OVERFLOW_HEURISTIC, 1,
-       [Define to 1 if extending the stack slightly past the limit causes
-	a SIGSEGV, and an alternate stack can be established with sigaltstack,
-	and the signal handler is passed a context that specifies the
-	run time stack.  This behavior is defined by POSIX 1003.1-2001
-        with the X/Open System Interface (XSI) option
-	and is a standardized way to implement a SEGV-based stack
-        overflow detection heuristic.])
-   fi])
-
-
-AC_DEFUN([gl_PREREQ_C_STACK],
-  [AC_REQUIRE([AC_SYS_XSI_STACK_OVERFLOW_HEURISTIC])
-
-   # for STACK_DIRECTION
-   AC_REQUIRE([AC_FUNC_ALLOCA])
-
-   AC_CHECK_FUNCS(getcontext sigaltstack)
-   AC_CHECK_DECLS([getcontext], , , [#include <ucontext.h>])
-   AC_CHECK_DECLS([sigaltstack], , , [#include <signal.h>])
-
-   AC_CHECK_HEADERS_ONCE(sys/time.h unistd.h)
-   AC_CHECK_HEADERS(sys/resource.h ucontext.h)
-
-   AC_CHECK_MEMBERS([struct sigaction.sa_sigaction], , , [#include <signal.h>])
-
-   AC_CHECK_TYPES([stack_t], , , [#include <signal.h>])])
-
 AC_DEFUN([gl_C_STACK],
 [
   dnl Prerequisites of lib/c-stack.c.