[Bug c++/92679] Test case with failing unordered_map search when key is type_index

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92679

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Change the capture from [&f] to simply [f] and it works fine.