The attach patch shuffles lines around to eliminate 80
lines of #ifdef...#endif; thereby making the file more
readable.  Tested on i586-*-freebsd and x86_64-*-freebsd.
Patch is a pre-requisite to fixing issues and adding 
missing functionality.  OK to commit?

2018-12-18  Steven G. Kargl  <kargl@gcc.gnu.org>

	* libgfortran/ieee/ieee_arithmetic.F90: Re-organize file to 
	eliminate excessive #ifdef ... #endif.

-- 
Steve