RFA: Fix calculation of size of builtin setjmp buffer

[Nick Clifton <nickc@redhat.com>]

Hi Guys,

  There is a small bug in the computation for the size of the builtin
  setjmp buffer.  The size is based upon BITS_PER_WORD / POINTER_SIZE
  which for most targets equates to 1.  But for targets where pointers
  are larger than a word, it equates to zero.  This leads to stack
  corruption and all kinds of fun things.

  The patch is obvious - see below - but since it affects generic code
  and might have consequences which I have not foreseen, I thought it
  best to ask for approval first.

  No regressions with an x86_64-pc-linux toolchain, and quite a few G++
  testsuite fixes for an rl78-elf toolchain.

  OK to apply ?

Cheers
  Nick

2014-05-06  Nick Clifton  <nickc@redhat.com>

	* except.c (init_eh): Fix computation of builtin setjmp buffer
	size.

Index: gcc/except.c
===================================================================
--- gcc/except.c	(revision 210096)
+++ gcc/except.c	(working copy)
@@ -287,7 +287,7 @@
 #endif
 #else
       /* builtin_setjmp takes a pointer to 5 words.  */
-      tmp = size_int (5 * BITS_PER_WORD / POINTER_SIZE - 1);
+      tmp = size_int (5 * POINTER_SIZE / BITS_PER_WORD - 1);
 #endif
       tmp = build_index_type (tmp);
       tmp = build_array_type (ptr_type_node, tmp);