bug in gmp_fprintf?

[paul zimmermann]

       Torbjörn,

> In reproducing the error, I ran into embarrassingly slow code in
> scanf/doscan.c; we read a byte at a time through a callback (see GET())
> and test the base argument in a tight, serially dependent loop.

I'm glad if this helps to improve gmp_scanf.

By the way, saying "Issues with GMP 6.0.0: [No issues found yet.]" on
gmplib.org/#STATUS is not quite correct. I remember at least the following
bugs which were acknowledged by the developers:

https://gmplib.org/list-archives/gmp-bugs/2015-March/003607.html
https://gmplib.org/list-archives/gmp-bugs/2015-September/003720.html

Paul