u32 and towupper

[Mike Gran]

Hi-

As far as I can tell, the ISO C towupper will probably work correctly on UCS-4 
characters created by Gnulib functions like u32_conv_from_enc.  But, it seems 
that it isn't guaranteed to do so, since wint_t is not required to be UCS-4.  
(I don't have a counterexample: I'm just going from what I've read.)

If that is true, then it would be neat to have u32_toupper and u32_tolower 
functions.  

Thanks,

Mike Gran