Make zn_poly respect the CC environment variable, work around GCC 4.7.0 bug on ia64 (and clean up the spkg)

Imported from <a href="http://trac.sagemath.org/sage_trac/ticket/12433">trac #12433</a>.

New / modified patch to `src/makemakefile.py`.  For easier review only; do not apply.

Reported by: rohana

Component: packages

CC: roed

Report Upstream: N/A

Authors: R. Andrew Ohana, Leif Leonhardy

Dependencies: 

Work issues: 

Reviewers: Leif Leonhardy, Jeroen Demeyer

Merged in: sage-5.2.beta1

Attachments: <ol><li><a href="http://trac.sagemath.org/sage_trac/attachment/ticket/12433/zn_poly-0.9.p6.patch">zn_poly-0.9.p6.patch: for review purposes</a> by rohana at 20120204T18:07:26</li><li><a href="http://trac.sagemath.org/sage_trac/attachment/ticket/12433/zn_poly-0.9.p6-p7.diff">zn_poly-0.9.p6-p7.diff: Diff between Andrew's and my new spkg.  For reference / review only.</a> by leif at 20120408T12:34:14</li><li><a href="http://trac.sagemath.org/sage_trac/attachment/ticket/12433/zn_poly-0.9.p5-p7.diff">zn_poly-0.9.p5-p7.diff: Diff between the previous spkg in Sage and my new spkg.  For reference / review only.</a> by leif at 20120408T12:35:06</li><li><a href="http://trac.sagemath.org/sage_trac/attachment/ticket/12433/zn_poly-0.9.p7-p8.diff">zn_poly-0.9.p7-p8.diff: Diff between my p7 and p8 spkgs.  For reference / review only.</a> by leif at 20120420T03:38:25</li><li><a href="http://trac.sagemath.org/sage_trac/attachment/ticket/12433/zn_poly-0.9.p5-p8.diff">zn_poly-0.9.p5-p8.diff: Diff between the p5 and p8 spkgs. For reference / review only. </a> by jdemeyer at 20120528T17:35:59</li><li><a href="http://trac.sagemath.org/sage_trac/attachment/ticket/12433/makemakefile.py.patch">makemakefile.py.patch: New / modified patch to `src/makemakefile.py`.  For easier review only; do not apply.</a> by jdemeyer at 20120528T17:38:00</li></ol>