Some compilers try/fail to load varargs.h

[jberger]

See example here:

http://www.cpantesters.org/cpan/report/24221dfb-e517-1014-bfab-11462b825c07

The problems are related to: http://mingw-cross-env-list.nongnu.narkive.com/zhn1u7zs/gsl-1-14-failing

[plicease]

My feeling is that this is an issue with GSL, if it still exists, unless there is an easy patch that we can apply to the source.