* automake.in (handle_source_transform): Call

* automake.in (handle_source_transform): Call
define_objects_from_sources() instead of calling
variable_value_as_list(), handle_single_transform_list() and
define_pretty_variable() directly.
(handle_single_transform_list): Add $topparent parameter, used for
error messages.  Improved error message.
(define_objects_from_sources): New function.
(subobjname): New function.
(variable_conditions_recursive): New name for variable conditions.
(variable_value_as_list_recursive): New name for variable_value_as_list.
(variable_value_as_list_worker): Renamed to ...
(variable_value_as_list_recursive_worker): ... this.
(variable_conditions_sub): Renamed to ...
(variable_conditions_recursive_sub): ... this.
(variable_conditions): Rewritten: now doesn't recurse subvariables.
(variable_value_as_list): Rewritten: now doesn't recurse subvariables.
(substfroms): New global.
(substtos): New global.
(substnums): New global.
* tests/cond3.test: Update to work with new method of defining _OBJECTS.
* tests/cond4.test: Update to work with new method of defining _OBJECTS.
* tests/sourcesub2.test: New test.
* tests/Makefile.am (TEST): Added sourcesub2.test.