I provided a third patch that uses - as a workaround - the fact that libsingular is able to create missing gftables files.
On Singular trac, Hannes said "No, gftables are parts of the sources and will be copied during installation, but usually not computed (the program for that, a part of factory, will not be build during a standard compilation and installation).
So, I wonder why the files aren't copied on Solaris and how libsingular is able to create them. But I think the third patch (that isn't tested, yet) should suffice to make the doc tests of the first two patches work on solaris.
Back to "needs review" - I hope that someone can doctest on Solaris.