Added simpler test case for C_Descriptor

Cases/Fortran2018/C_DescriptorSimple/C_Desc.c

+
+#include <stdlib.h>
+#include <stdio.h>
+#include "ISO_Fortran_binding.h"
+
+void C_Desc ( CFI_cdesc_t *A_DV )
+  {
+  printf("A_DV.rank: %d\n", A_DV->rank );
+  }

Cases/Fortran2018/C_DescriptorSimple/C_Desc.f90

+module C_DescMod
+
+  use iso_c_binding
+  
+  implicit none
+  public
+  
+  interface
+    subroutine C_Desc ( A ) bind ( c, name = 'C_Desc' )
+      use iso_c_binding
+      implicit none
+      real, dimension ( :, :, : ), allocatable, &
+        intent ( out ) :: &
+          A
+    end subroutine C_Desc
+  end interface
+  
+end module C_DescMod
+
+program C_DescProg
+  
+  use C_DescMod
+  implicit none
+  
+  real, dimension ( :, :, : ), allocatable :: &
+    Array
+
+  print*, 'Fortran: rank:', rank ( Array )
+  call C_Desc ( Array )
+  
+end program C_DescProg