dfa.c fix for C89 compilers

[Aharon Robbins]

Index: dfa.c
===================================================================
RCS file: /d/mongo/cvsrep/gawk-stable/dfa.c,v
retrieving revision 1.27
diff -u -r1.27 dfa.c
--- dfa.c       29 Mar 2010 02:58:08 -0000      1.27
+++ dfa.c       31 Mar 2010 12:45:16 -0000
@@ -2781,6 +2781,7 @@
   unsigned char eol = eolbyte; /* Likewise for eolbyte.  */
   static int sbit[NOTCHAR];    /* Table for anding with d->success. */
   static int sbit_init;
+  unsigned char saved_end;
 
   if (! sbit_init)
     {
@@ -2798,7 +2799,7 @@
   s = s1 = 0;
   p = (unsigned char const *) begin;
   trans = d->trans;
-  unsigned char saved_end = *(unsigned char *) end;
+  saved_end = *(unsigned char *) end;
   *end = eol;
 
 #ifdef MBS_SUPPORT