Fix ptype bug actually exercised in userdef.exp

Fix ptype bug actually exercised in userdef.exp

I happened to notice a bug with ptype &Ref, and found out userdef.exp
actually exercises the bug.  With:

class Container
{
public:
  Member m;

  Member& operator* ();
};

Member& Container::operator* ()
{
  return this->m;
}

And 'c' is of type Container:

(gdb) p c
$1 = {m = {z = -9192}}
(gdb) p *c
$2 = (Member &) @0x7fffffffda20: {z = -9192}
(gdb) ptype *c
type = class Member {
  public:
    int z;
} &

(gdb) p &*c
$3 = (Member *) 0x7fffffffda20

(gdb) ptype &*c
type = class Member {
  public:
    int z;
} &*
(gdb)

Notice that last print (&*c) on says the type is a pointer - that's
how you get the address behind a reference.  But notice the last ptype
instead says the type of the same expression is a pointer _reference_.
This looks like a bug to me.

This patch fixes it.  The issue is that we're entering the VALUE_LVAL
(x) == lval_memory branch by mistake for references.  The fix is just
to swap the tests so references are checked first, like value_addr
also handles references first.

Tested on x86_64 Fedora 17.

2013-02-14  Pedro Alves  <palves@redhat.com>

	* eval.c (evaluate_subexp_for_address) <default_case_after_eval,
	EVAL_AVOID_SIDE_EFFECTS>: Swap and handle TYPE_CODE_REF before
	lval_memory.

2013-02-14  Pedro Alves  <palves@redhat.com>

	* gdb.cp/userdef.exp (ptype &*c): Don't expect an &.