cvs build fails in fold-const.c

[Billinghurst, David (CRTS)]

Current CVS build using cc on irix6.5 fails in fold_const.c with 

"/exd4/billingd/src/gcc/gcc/fold-const.c", line 7179: error(1140): a value
of
          type "int" cannot be used to initialize an entity of type "tree"
          tree tmp = fold_builtin (expr);

fold_builtin is conditionally defined in expr.h, but including this header
seemed to make things worse.