libio patches for glibc 2.1

[Jason Merrill]

>>>>> H J Lu <hjl@lucon.org> writes:

>> >>>>> Jeffrey A Law <law@cygnus.com> writes:
>> 
>> > We need patches for:
>> 
>> >     * A fix for the sigset_t problem.  I've got no opinion on what
>> >     the best fix is -- I'm depending on y'all to make that technical
>> >     decision.    
>> 
>> Fixed.
>> 

> I think that fix breaks glibc 2.1 and glibc 2.0.7.

Why?  How?  Please be more specific.

Jason