remove unnecessary cast from reduce.c

[Paul Eggert]

The cast to bool dates back to 1994, when bool was still problematic.
It's no longer needed, so I installed this:

2006-01-03  Paul Eggert  <address@hidden>

        * src/reduce.c (reduce_grammar): Remove unnecessary cast to bool.

--- src/reduce.c.~1.87.~        2005-12-09 15:51:26.000000000 -0800
+++ src/reduce.c        2006-01-03 14:21:12.000000000 -0800
@@ -426,7 +426,7 @@ reduce_grammar (void)
   useless_nonterminals ();
   inaccessable_symbols ();
 
-  reduced = (bool) (nuseless_nonterminals + nuseless_productions > 0);
+  reduced = (nuseless_nonterminals + nuseless_productions > 0);
   if (!reduced)
     return;