[PATCH] Fix libstdc++/5045 (take3)

[Paolo Carlini]

Please scratch my last message and the corresponding "improvement" :(
In fact 64 bit unsigned integers are not special at all: max num digits == digits10 + 1 for them
too. They are "special" only in that the current value of digits10 in std_limits.h is the only one
correct (as was pointed out by Philip right from the beginning of libstdc++/5045 trail)

Therefore the simpler "take3" was perfectly ok:

    http://gcc.gnu.org/ml/libstdc++/2001-12/msg00161.html


This digits10 issue is quite tricky, isn't it?

Cheers,
Paolo.