coarray_40.f90: Link with libatomic if available.

	* gfortran.dg/coarray_40.f90: Link with libatomic if available.

From-SVN: r231981

gcc/testsuite/ChangeLog

 2015-12-28  John David Anglin  <danglin@gcc.gnu.org>
 
+	* gfortran.dg/coarray_40.f90: Link with libatomic if available.
+
 	* gcc.dg/pr49551.c: Skip on hppa*-*-hpux*.
 
 	* gcc.dg/torture/pr67609.c: Add -fno-common option on hppa*-*-hpux*.

gcc/testsuite/gfortran.dg/coarray_40.f90

 ! { dg-do run }
-! { dg-options "-fcoarray=lib -lcaf_single" }
+! { dg-options "-fcoarray=lib -lcaf_single -latomic" { target libatomic_available } }
+! { dg-options "-fcoarray=lib -lcaf_single" { target { ! libatomic_available } } }
 !
 ! Run-time test for memory consistency
 !