[Bug libstdc++/60401] stdlib.h does not provide abs(long) overload

[vogt at linux dot vnet.ibm.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60401

--- Comment #12 from Dominik Vogt <vogt at linux dot vnet.ibm.com> ---
Regarding the Glibc fix; do you mean this commit?

  2016-01-11 13:34 Adhemerval Zanella               * Fix isinf/isnan
declaration conflict with C++11

That does *not* fix the isnan and isinf errors.