Note: This is a gnulib issue having two different ways to be fixed. The patch from Alan Modra:
https://lists.gnu.org/archive/html/bug-gnulib/2013-12/msg00104.html and the patch from Ulrich Weigand: https://lists.gnu.org/archive/html/bug-gnulib/2013-12/msg00107.html but I did "git blame tests/test-isnanl.h" and this seems not to be fixed yet.
