RFA: don't try to compare IEEE NaN's

[Eli Zaretskii]

> From: Jim Blandy <jimb@zwingli.cygnus.com>
> Date: Tue,  5 Jun 2001 22:41:45 -0500 (EST)
> 
> !   testval.float_testval = 2.7182818284590452354;/* long_long_checkpoint */
> !   float_resultval     = float_func ();		
> !   testval.double_testval = 3.14159265358979323846; /* float_checkpoint */
> !   double_resultval    = double_func ();		

I think it is better to initialize the integral members of the union
with an explicit bit pattern, just not a pattern which gets
interpreted as a NaN of an Inf.  With initialization such as above,
you risk losing due to subtleties of compile-time conversion of a
literal constant to a floating-point value.  This is a GDB test suite,
so we are not interested in testing the compiler.