patch applied (ghc-6.12/ghc): Explicitly check whether ar supports the @file syntax

[Ian Lynagh]

Mon Mar 29 05:33:25 PDT 2010  Ian Lynagh <igloo at earth.li>
  * Explicitly check whether ar supports the @file syntax
  rather than assuming that all GNU ar's do.
  Apparently OpenBSD's older version doesn't.

    M ./aclocal.m4 +26
    M ./configure.ac -1 +1
    M ./mk/config.mk.in -1 +1
    M ./rules/build-package-way.mk -1 +1