GHC-6.12.1: broken configure

[Kirill A. Shutemov]

I want to build ghc for i586-alt-linux-gnu.

> ./configure --host=i586-alt-linux-gnu --build=i586-alt-linux-gnu
checking for gfind... no
checking for find... /bin/find
checking for sort... /bin/sort
checking for ghc... /usr/bin/ghc
checking version of ghc... 6.10.1
Target platform inferred as: i386-unknown-linux
Unknown arch i586

Why i586 is unknown? It's a valid architecture.
Why does it check vendor? Many of distribution define own vendor.
Why do not use config.guess to guess correct host/target/build
instead of reinvent wheel?

Please fix it. It will simplify packaging GHC for distributions.