Bugfix for unpromoted ddt-type scalar variables (#626)

Fixes a bug where a ddt used in only one phase (thereby not promoted to
the group level) does not get the necessary "use" statement added at the
subroutine level in the suite cap.

scripts/suite_objects.py

@@ -2485,7 +2485,9 @@ def write(self, outfile, host_arglist, indent, const_mod,
         call_vars = self.call_list.variable_list()
         self._ddt_library.write_ddt_use_statements(call_vars, outfile,
                                                    indent+1, pad=modmax)
-        decl_vars = [x[0] for x in subpart_allocate_vars.values()]
+        decl_vars = ([x[0] for x in subpart_allocate_vars.values()] +
+                     [x[0] for x in subpart_scalar_vars.values()] +
+                     [x[0] for x in subpart_optional_vars.values()])
         self._ddt_library.write_ddt_use_statements(decl_vars, outfile,
                                                    indent+1, pad=modmax)
         outfile.write('', 0)