Using wrong libgcc_s when building gcc

[vbraun]

Building with SAGE_INSTALL_GCC=yes fails on Debian 9 32-bit:

[dochtml] Setting permissions of DOT_SAGE directory so only you can read and write it.
[dochtml] Traceback (most recent call last):
[dochtml]   File "/home/buildbot/slave/binary_pkg/build/source/SageMath/jc4b6yulaujayb9sr94ia88eourzeqip0oidmas391yaj2/local/lib/python2.7/runpy.py", line 163, in _run_module_as_main
[dochtml]     mod_name, _Error)
[dochtml]   File "/home/buildbot/slave/binary_pkg/build/source/SageMath/jc4b6yulaujayb9sr94ia88eourzeqip0oidmas391yaj2/local/lib/python2.7/runpy.py", line 111, in _get_module_details
[dochtml]     __import__(mod_name)  # Do not catch exceptions initializing package
[dochtml]   File "/home/buildbot/slave/binary_pkg/build/source/SageMath/jc4b6yulaujayb9sr94ia88eourzeqip0oidmas391yaj2/local/lib/python2.7/site-packages/sage_setup/docbuild/__init__.py", line 54, in <module>
[dochtml]     import sage.all
[dochtml]   File "/home/buildbot/slave/binary_pkg/build/source/SageMath/jc4b6yulaujayb9sr94ia88eourzeqip0oidmas391yaj2/local/lib/python2.7/site-packages/sage/all.py", line 94, in <module>
[dochtml]     from sage.rings.all      import *
[dochtml]   File "/home/buildbot/slave/binary_pkg/build/source/SageMath/jc4b6yulaujayb9sr94ia88eourzeqip0oidmas391yaj2/local/lib/python2.7/site-packages/sage/rings/all.py", line 88, in <module>
[dochtml]     from .qqbar import (AlgebraicRealField, AA,
[dochtml]   File "/home/buildbot/slave/binary_pkg/build/source/SageMath/jc4b6yulaujayb9sr94ia88eourzeqip0oidmas391yaj2/local/lib/python2.7/site-packages/sage/rings/qqbar.py", line 2153, in <module>
[dochtml]     QQxy = QQ['x', 'y']
[dochtml]   File "sage/structure/parent.pyx", line 1224, in sage.structure.parent.Parent.__getitem__ (build/cythonized/sage/structure/parent.c:11402)
[dochtml]   File "/home/buildbot/slave/binary_pkg/build/source/SageMath/jc4b6yulaujayb9sr94ia88eourzeqip0oidmas391yaj2/local/lib/python2.7/site-packages/sage/categories/rings.py", line 1087, in __getitem__
[dochtml]     return PolynomialRing(self, elts)
[dochtml]   File "/home/buildbot/slave/binary_pkg/build/source/SageMath/jc4b6yulaujayb9sr94ia88eourzeqip0oidmas391yaj2/local/lib/python2.7/site-packages/sage/rings/polynomial/polynomial_ring_constructor.py", line 648, in PolynomialRing
[dochtml]     return _multi_variate(base_ring, names, **kwds)
[dochtml]   File "/home/buildbot/slave/binary_pkg/build/source/SageMath/jc4b6yulaujayb9sr94ia88eourzeqip0oidmas391yaj2/local/lib/python2.7/site-packages/sage/rings/polynomial/polynomial_ring_constructor.py", line 776, in _multi_variate
[dochtml]     from sage.rings.polynomial.multi_polynomial_libsingular import MPolynomialRing_libsingular
[dochtml] ImportError: /lib/i386-linux-gnu/libgcc_s.so.1: version `GCC_7.0.0' not found (required by /home/buildbot/slave/binary_pkg/build/source/SageMath/jc4b6yulaujayb9sr94ia88eourzeqip0oidmas391yaj2/local/lib/libSingular-4.1.1.so)

[vbraun]

Somewhere the wrong libgcc_s is being loaded first; by the time libSingular wants to load the correct one (inside Sage) its too late and the version mismatch occurs.

[vbraun]

Nevermind this is #25996