Fix processing of ADDR_EXPR in get_expr_operands

[Richard Kenner]

    I *told* you.  The variable is *local*, and thus TREE_INVARIANT
    is the correct bit to set, not TREE_CONSTANT.

Oh, sorry.  I've never heard of a use for a volatile *local* variable, so
I just assumed it was global and hence that TREE_CONSTANT would apply.

I'll do a bootstrap soon and see if the motivation for using TREE_CONSTANT
instead of TREE_INVARIANT there is still present.