U-boot building problem. please advice

[Ilya Krasavin]

Hello.
I try to build the latest stable version of U-Boot for Arria5 (Arm32
bit) on Cygwin. I prefer teh Cygwin since in my company there is no
Linux computers in the corporate network.
The reason that I started to do it - the vendor provides u-boot for
that chip, but it is from 2013, so it is the old version of everything
(u-boot, toolchain, cygwin) and it is never updated by the vendor and
therefore I need to do it by myself.

1. Could you recommend a specific toolchain (shall it be arm-eabi or
arm-linux-gnueabi)?
2. I found that the makefile adds "-ansi" flag for cygwin, which leads
to immediate failure. What was the reason for adding this flag?
3, I didn't find on the internet too much helpful information about
that, so  I'd be very grateful if anyone can share with me his
knowledge.

Thanks in advance.
Ilya