Let gf2x build a shared library on Cygwin

[jpflori]

This is related to #13354.
Reported upstream which waits for a proper fix form my side...

Use:

• http://boxen.math.washington.edu/home/jpflori/spkg/gf2x-1.1.p0.spkg

Upstream: Reported upstream. Developers acknowledge bug.

CC: @kcrisman @dimpase @tscrim

Component: porting: Cygwin

Keywords: gf2x spkg cygwin

Author: Jean-Pierre Flori

Reviewer: Travis Scrimshaw

Merged: sage-5.12.beta2

Issue created by migration from https://trac.sagemath.org/ticket/15014

[jpflori]

Attachment: gf2x-1.1.p0.diff.gz

Spkg diff, for review only.

[tscrim]

comment:2

Looks good to me. Built on cygwin64 and I'll double-check on cygwin32 in a bit and report if there's a failure.

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

comment:3

Also works on cygwin32.

[jdemeyer]

Merged: sage-5.12.beta2