Remove ibf_dumper's WB_PROTECTED status

	It doesn't have the right write barriers in place. For example, there is

	    rb_mark_set(dump->global_buffer.obj_table);

	in the mark function, but there is no corresponding write barrier when
	adding to the table in the
	`ibf_dump_object() -> ibf_table_find_or_insert() -> st_insert()` code path.

	To insert write barrier correctly, we need to store the T_STRUCT VALUE
	inside `struct ibf_dump`. Instead of doing that, let's just demote it
	to WB unproected for correctness. These dumper object are ephemeral so
	there is not a huge benefit for having them WB protected.

	Users of the bootsnap gem ran into crashes due to this issue:
	https://github.com/Shopify/bootsnap/issues/436

	Fixes [Bug #19419]
	---
	 compile.c | 2 +-
	 1 file changed, 1 insertion(+), 1 deletion(-)