Add caf-shared subdirectory to gfortran.dg with passing tests.

Add caf-shared subdirectory to gfortran.dg with passing tests.

gcc/testsuite/ChangeLog:

	* gfortran.dg/caf-shared/cas.exp: New file.
	* gfortran.dg/caf-shared/alloc_comp_1.f90: New test.
	* gfortran.dg/caf-shared/arg_passing_1.f90: New test.
	* gfortran.dg/caf-shared/assign_array_1.f90: New test.
	* gfortran.dg/caf-shared/atomic_1.f90: New test.
	* gfortran.dg/caf-shared/coarray_40.f90: New test.
	* gfortran.dg/caf-shared/codimension_2.f90: New test.
	* gfortran.dg/caf-shared/codimension_2a.f90: New test.
	* gfortran.dg/caf-shared/codimension_2b.f90: New test.
	* gfortran.dg/caf-shared/collectives_1.f90: New test.
	* gfortran.dg/caf-shared/collectives_2.f90: New test.
	* gfortran.dg/caf-shared/collectives_4.f90: New test.
	* gfortran.dg/caf-shared/cosubscript_1.f90: New test.
	* gfortran.dg/caf-shared/data_1.f90: New test.
	* gfortran.dg/caf-shared/dummy_1.f90: New test.
	* gfortran.dg/caf-shared/image_index_2.f90: New test.
	* gfortran.dg/caf-shared/num_images_1.f90: New test.
	* gfortran.dg/caf-shared/subobject_1.f90: New test.
	* gfortran.dg/caf-shared/this_image_1.f90: New test.
	* gfortran.dg/caf-shared/this_image_2.f90: New test.