[wp] remove spurious typedefs in some tests

src/plugins/wp/tests/wp_acsl/assigns_path.i

src/plugins/wp/tests/wp_bts/bts_2079.i

src/plugins/wp/tests/wp_plugin/dynamic.i

src/plugins/wp/tests/wp_usage/caveat.i

src/plugins/wp/tests/wp_usage/caveat2.i