Fix hashing of multiply and add

[Jan Hubicka]

Hi,
I have noticed that hash_operand computes a hash value that is unused
since two is a local variable.  This patch fixes it.

Bootstrapped/regtested x86_64-linux, OK?

        * fold-const.c (operand_compare::hash_operand): Fix hashing of operand
        3 of multiply and add.
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index c47557daeba..8844069127c 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -3806,7 +3806,7 @@ operand_compare::hash_operand (const_tree t, 
inchash::hash &hstate,
                hash_operand (TREE_OPERAND (t, 0), one, flags);
                hash_operand (TREE_OPERAND (t, 1), two, flags);
                hstate.add_commutative (one, two);
-               hash_operand (TREE_OPERAND (t, 2), two, flags);
+               hash_operand (TREE_OPERAND (t, 2), hstate, flags);
                return;
              }