Move gfortran.dg/dec_math_5.f90 to ./ieee/

	PR fortran/93871
	* gfortran.dg/dec_math_5.f90: Move to ...
	* gfortran.dg/ieee/dec_math_1.f90: ... here; change
	dg-options to dg-additional-options.

gcc/testsuite/ChangeLog

+2020-04-08  Tobias Burnus  <tobias@codesourcery.com>
+
+	PR fortran/93871
+	* gfortran.dg/dec_math_5.f90: Move to ...
+	* gfortran.dg/ieee/dec_math_1.f90: ... here; change
+	dg-options to dg-additional-options.
+
 2020-04-08  Alexandre Oliva <oliva@adacore.com>
 
 	* gcc.dg/tls/pr78796.c: Require tls_runtime.

gcc/testsuite/gfortran.dg/dec_math_5.f90 → gcc/testsuite/gfortran.dg/ieee/dec_math_1.f90

-! { dg-options "-cpp -std=gnu" }
 ! { dg-do run }
+! { dg-additional-options "-cpp -std=gnu" }
 !
 ! Test values for degree-valued trigonometric intrinsics.
 !
+! Run under ieee/ as
+!   use ieee_arithmetic
+! (used for result checking) is not available on all platforms)
 
 module dec_math_5