Yet more work to reject old libstdc++

Sadly there isn't any standard way to detect this, but hopeully these
hacks should suffice

Author: mitchblank

timsort.hpp

@@ -62,10 +62,37 @@
 #    if defined(__cplusplus) && __cplusplus < 201103L
 #      undef GFX_TIMSORT_USE_CXX11
 #    endif
-#    ifdef __GLIBCXX__
+#    ifdef _GLIBCXX_RELEASE
+       // This setting only got added in gcc 7.1, so its presence always
+       // indicates a C++11-ready STL
+#    elif defined(__GLIBCXX__)
+       // Before 7.1, the only way to test the version of libstdc++ is the
+       // __GLIBCXX__ date macro.  However, it's not monotonically increasing
+       // releases kepy being made from older branches.  The best we can do is
+       // to disallow any version that is definitely before gcc 5.1 (the first
+       // version that had enough C++11 support for us) and then blacklist
+       // dates that are known to correspond with non-working versions.
+       //
+       // Note this really only is a problem when mixing compilers and STL (i.e.
+       // compiling using clang but using gcc's libstdc++)   Otherwise we'll
+       // correctly reject the gcc compiler if its too old later.
 #      if __GLIBCXX__ < 20150422
 #        undef GFX_TIMSORT_USE_CXX11
 #      endif
+#      if __GLIBCXX__ == 20150426
+#        undef GFX_TIMSORT_USE_CXX11   // gcc 4.8.4+patches shipped with Ubuntu LTS 14.04
+#      endif
+#      if __GLIBCXX__ == 20150623
+#        undef GFX_TIMSORT_USE_CXX11   // gcc 4.8.5
+#      endif
+#      if __GLIBCXX__ == 20150626
+#        undef GFX_TIMSORT_USE_CXX11   // gcc 4.9.3
+#      endif
+#      if __GLIBCXX__ == 20160803
+#        undef GFX_TIMSORT_USE_CXX11   // gcc 4.9.5
+#      endif
+#    elif defined(__GLIBCPP__)  // *really* old version of libstdc++
+#      undef GFX_TIMSORT_USE_CXX11
 #    endif
 #    ifdef _LIBCPP_VERSION
 #      if defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) || defined(_LIBCPP_CXX03_LANG)