I was trying to build rpm on Windows, inside the MSYS2 environment.
It complained about not being able to detect the system, so I downloaded fresh config.guess and config.sub. Looks like MSYS2 support is missing.
Here is what I was "told" by the script to send to you (I hope this helps):
config.guess timestamp = 2014-02-12
uname -m = x86_64
uname -r = 2.0.0(0.271/5/3)
uname -s = MSYS_NT-6.1
uname -v = 2014-03-04 15:59
/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 = 2.0.0(0.271/5/3)
UNAME_SYSTEM = MSYS_NT-6.1
UNAME_VERSION = 2014-03-04 15:59
--
Dejan Lekic
http://dejan.lekic.org