patch applied (packages/readline): Link against GNUreadline.framework, if it's available.

[Ian Lynagh]

Wed Sep  5 22:26:28 PDT 2007  judah.jacobson at gmail.com
  * Link against GNUreadline.framework, if it's available.
  This can be overridden by setting --with-readline-includes or 
  --with-readline-libraries.

    M ./HsReadline_cbits.c -2 +1
    M ./configure.ac -20 +39
    M ./include/HsReadline.h -1 +7
    M ./readline.buildinfo.in +1