patch applied (packages/unix): Allow C's unsetenv to return either void or int

[Ian Lynagh]

Thu Jul  3 12:06:03 PDT 2008  Ian Lynagh <igloo at earth.li>
  * Allow C's unsetenv to return either void or int
  Fixes, and patch from donn in, trac #2352.

    M ./System/Posix/Env.hsc -3 +4
    M ./configure.ac +13
    M ./include/HsUnix.h +10

View patch online:
http://darcs.haskell.org/packages/unix/_darcs/patches/20080703190603-3fd76-bef431f159e92151b49edbb5bcdc748145b98753.gz