Allow building Sage with GCC-4.7.x

Imported from <a href="http://trac.sagemath.org/sage_trac/ticket/12751">trac #12751</a>.

Apply to SAGE_ROOT

Reported by: mariah

Component: build

CC: jdemeyer,, leif

Report Upstream: N/A

Authors: Jeroen Demeyer

Dependencies: 

Work issues: 

Reviewers: Volker Braun

Merged in: sage-5.2.beta1

Attachments: <ol><li><a href="http://trac.sagemath.org/sage_trac/attachment/ticket/12751/ecm-6.3.p8.diff">ecm-6.3.p8.diff: Diff for the ecm spkg. For reference / review only.</a> by jdemeyer at 20120529T02:21:29</li><li><a href="http://trac.sagemath.org/sage_trac/attachment/ticket/12751/mpfr-3.1.0.p2.diff">mpfr-3.1.0.p2.diff: Diff for the mpfr spkg. For reference / review only.</a> by jdemeyer at 20120529T02:21:46</li><li><a href="http://trac.sagemath.org/sage_trac/attachment/ticket/12751/mpir-2.4.0.p6.diff">mpir-2.4.0.p6.diff: Diff for the mpir spkg. For reference / review only.</a> by jdemeyer at 20120529T02:22:04</li><li><a href="http://trac.sagemath.org/sage_trac/attachment/ticket/12751/zn_poly-0.9.p9.diff">zn_poly-0.9.p9.diff: Diff for the zn_poly spkg. For reference / review only.</a> by jdemeyer at 20120529T02:22:21</li><li><a href="http://trac.sagemath.org/sage_trac/attachment/ticket/12751/12751_allow_gcc_4_7.patch">12751_allow_gcc_4_7.patch: Apply to SAGE_ROOT</a> by jdemeyer at 20120529T03:02:24</li></ol>