relax requirements for vector==

[Richard Andrews]

>From veksler@il.ibm.com (Tuesday 06 March 2001 22:25)
> Oops, just found out that my patch won't work due to:
> __STL_REQUIRES(........    _EqualityComparable)
>
> What is the idea behind these overly strong assertions? "If I'll make it in
> gcc I will make it anywhere"?

I'd also be interested in this.

I came across some particularly draconian requirements when using 
std::advance(), had to end up writing a loop to do what should have been one 
statement.