building gmp-6.1 for s390 (31-bit) w/asm disabled failing with undefined sdiv_qrnnd

[paul zimmermann]

       Hi Torbjörn,

> We're probably going to create many more problems for extension libs for
> GMP 7.  It will be the first release to support symbol hiding, and while
> we're not going to be fascist about our "private" symbols, we're going
> to make truly internal things hidden.

then please add in the interface symbols which are useful to extension libs,
see for example https://gmplib.org/list-archives/gmp-devel/2016-July/004306.html.

Paul