config.guess fails on appveyor

[Juppit]

Config.guess fails to detect Cygwin64 on AppVeyor.

> This script (version 2018-03-08), has failed to recognize the
> operating system you are using. If your script is old, overwrite *all*
> copies of config.guess and config.sub with the latest versions from:
>   https://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess
> and
>   https://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub
> If ./config.guess has already been updated, send the following data and any
> information you think might be pertinent to address@hidden to
> provide the necessary information to handle your system.
> config.guess timestamp = 2018-03-08
> uname -m = x86_64
> uname -r = 2.10.0(0.325/5/3)
> uname -s = Cygwin64_NT-10.0
> uname -v = 2018-02-09 15:25
> /usr/bin/uname -p = unknown
> /bin/uname -X     = 
> hostinfo               = 
> /bin/universe          = 
> /usr/bin/arch -k       = 
> /bin/arch              = x86_64
> /usr/bin/oslevel       = 
> /usr/convex/getsysinfo = 
> UNAME_MACHINE = "x86_64"
> UNAME_RELEASE = "2.10.0(0.325/5/3)"
> UNAME_SYSTEM  = "Cygwin64_NT-10.0"
> UNAME_VERSION = "2018-02-09 15:25"

'uname -a' generates this:
> Cygwin64_NT-10.0 APPVYR-WIN 2.10.0(0.325/5/3) 2018-02-09 15:25 x86_64 Msys

To reproduce this easily see my small project:
https://github.com/Juppit/Check-CI

Regards Juppit