* automake.in (handle_lib_objects): Compute _DEPENDENCIES variables

* automake.in (handle_lib_objects): Compute _DEPENDENCIES variables
using transform_variable_recursively instead of
variable_conditions_recursive and variable_value_as_list_recursive
to avoid combinatorial explosion.
(handle_lib_objects_cond): Merge into handle_lib_objects.
* tests/cond11.test: Don't grep internal details in Makefile.in,
run $MAKE to make sure the resulting Makefile runs as expected.
* tests/cond29.test: Also exercise conditional _LDADD.
* tests/cond31.test, tests/cond32.test: New files.
* tests/Makefile.am (TESTS): Add tests/cond31.test and
tests/cond32.test.