Improve disclaim_bench and disclaim_test

Improve disclaim_bench and disclaim_test

* tests/disclaim_bench.c: Do not include assert.h.
* tests/disclaim_test.c: Likewise.
* tests/disclaim_bench.c (my_assert): New macro.
* tests/disclaim_test.c: Likewise.
* tests/disclaim_bench.c (testobj_finalize, testobj_new): Replace
assert with my_assert.
* tests/disclaim_test.c (misc_sizes_dct, test_misc_sizes, pair_dct,
pair_new, pair_check_rec): Likewise.
* tests/disclaim_test.c (misc_sizes_dct): Test "cd" value (at least to
prevent "unused argument" compiler warning).
* tests/disclaim_test.c (test_misc_sizes): Use ANSI C style of
function declaration.
* tests/disclaim_bench.c (fclos): Add 'const' qualifier (since
GC_finalized_malloc now accepts const pointer).
* tests/disclaim_test.c (test_misc_sizes, pair_new): Likewise.
* tests/disclaim_test.c (test_misc_sizes, pair_new): Test
GC_finalized_malloc result for NULL.