patch applied (ghc): Tweak the Makefile code for making .a libs; fixes trac #3642

[Ian Lynagh]

Tue Mar 23 15:13:25 PDT 2010  Ian Lynagh <igloo at earth.li>
  * Tweak the Makefile code for making .a libs; fixes trac #3642
  The main change is that, rather than using "xargs ar" we now put
  all the filenames into a file, and do "ar @file". This means that
  ar adds all the files at once, which works around a problem where
  files with the same basename in a later invocation were overwriting
  the existing file in the .a archive.

    M ./rules/build-package-way.mk -6 +7