Behaviour of invalid varobjs

[Vladimir Prus]

I think current mainline does something strange
about varobjs that cannot be evaluated:

        -var-create null_ptr * **0
        ^done,name="null_ptr",numchild="0",value="0",type="int"
        (gdb)
        -var-update null_ptr
        ^done,changelist=[{name="null_ptr",in_scope="false"}]

First, the value of "**0" is not 0, in fact there's no value at all.
Second, given that nothing was changed between the two commands,
it's strange that 'null_ptr' is mentioned in -var-update.

Before I go changing code, do everybody agree that:

1. The output of -var-create should either have no "value"
field at all, or value="", as is used in some other context.
2. The output of -var-update should not include anything.

Also, we probably should include in_scope="false" in output of
-var-create, but I'm not quite sure.

Comments?

- Volodya