libgfortran: Fix PR95647 by changing the interfaces of operators .eq. and .ne.

libgfortran: Fix PR95647 by changing the interfaces of operators .eq. and .ne.

The FE converts the old school .eq. to ==,
and then tracks the ==.  The module starts with == and so it does not
properly overload the .eq.  Reversing the interfaces fixes this.

2021-02-12  Steve Kargl <sgk@troutmask.apl.washington.edu>

libgfortran/ChangeLog:

	PR libfortran/95647
	* ieee/ieee_arithmetic.F90: Flip interfaces of operators .eq. to
	== and .ne. to /= .

gcc/testsuite/ChangeLog:

	PR libfortran/95647
	* gfortran.dg/ieee/ieee_12.f90: New test.