[Bug bootstrap/63622] [5.0 Regression] Bootstrap fails on x86_64-apple-darwin1[34] after revision r216305

[howarth at bromo dot med.uc.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63622

--- Comment #12 from howarth at bromo dot med.uc.edu ---
This looks like fallout from...

https://gcc.gnu.org/ml/libstdc++-cvs/2014-q4/msg00080.html
https://gcc.gnu.org/ml/libstdc++-cvs/2014-q3/msg00181.html

where the files moved to c++11 in gcc trunk from c++98 in gcc 4.9.2 now have
undefined symbols...

[MacPro:libstdc++-v3/src/c++11] howarth% nm streambuf-inst.o | grep
ZNSt15basic_streambufIcSt11char_traitsIcEE9underflowEv
                 U __ZNSt15basic_streambufIcSt11char_traitsIcEE9underflowEv


compared to gcc 4.9.2

[MacPro:libstdc++-v3/src/c++98] howarth% nm streambuf-inst.o | grep
ZNSt15basic_streambufIcSt11char_traitsIcEE9underflowEv
0000000000000040 T __ZNSt15basic_streambufIcSt11char_traitsIcEE9underflowEv

Were these checkins made after darwin stopped bootstrapping?