[Bug libstdc++/85813] make_exception_ptr should support __cxa_init_primary_exception path even with -fno-exceptions

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85813

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
... because if that constructor throws and the current translation unit is
built without exceptions, we can't catch it.