Much of test-qobject-input-strict.c duplicates
test-qobject-input-strict.c, but with less assertions on expected
output:

* test_validate_struct() duplicates test_visitor_in_struct()

* test_validate_struct_nested() duplicates
  test_visitor_in_struct_nested()

* test_validate_list() duplicates the first half of
  test_visitor_in_list()

* test_validate_union_native_list() duplicates
  test_visitor_in_native_list_int()

* test_validate_union_flat() duplicates test_visitor_in_union_flat()

* test_validate_alternate() duplicates the first part of
  test_visitor_in_alternate()

Merge the remaining test cases into test-qobject-input-visitor.c, and
drop the now redundant test-qobject-input-strict.c.

Test case "/visitor/input-strict/fail/list" isn't really about lists,
it's about a bad struct nested in a list.  Rename accordingly.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Message-Id: <1488544368-30622-21-git-send-email-armbru@redhat.com>