Add VIEW_CONVERT_EXPR to operand_equal_p

[Jan Hubicka]

> 
> Yeah, I suppose we'd need to either build a new function type for each
> variadic call
> then or somehow represent 'fntype' differently (note that function
> attributes also
> need to be preserved).

Why we can't keep fntype as it is, but simply add a new set of parameters to call stmt
that lists their types?  We can then feed those types to expand_call (since we still go
back to generic here I suppose we will just re-insert those VCEs in expand-cfg.c)

Honza