gsl_isnan in eigen/*.c for 1.3

[Albert Chin]

Why do eigen/symm.c, eigen/symmv.c, eigen/herm.c, and eigen/hermv.c
use gsl_isnan() rather than isnan()? gsl_isnan is defined only when
using Microsoft Visual C++ (sys/infnan.c) or if HAVE_IEEE_COMPARISONS
is defined. On HP-UX 10.20, HAVE_IEEE_COMPARISONS is not defined. As
isnan is defined to gsl_isnan in config.h, why not use isnan()?

Is it really bad for HP-UX 10.20 to fail the HAVE_IEEE_COMPARISONS
test?

Ditto for sys/test.c.

-- 
albert chin (china@thewrittenword.com)