Pass the unadjusted type into the unsize_info function, which seems to be what it expects. Fixes #17322.
auto merge of #18746 : nikomatsakis/rust/issue-17322-unsized_ty, r=ncr

Pass the unadjusted type into the unsize_info function, which seems to be what it expects. Fixes #17322.

r? @nick29581 

Full disclosure: still running make check locally ;)