[Bug target/70016] [6 Regression] pr52429.c fails since r233745

[ktkachov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70016

--- Comment #2 from ktkachov at gcc dot gnu.org ---
this_target_ira_int->x_init_cost is NULL when it's used, causing the ICE.
I would have expected target_reinit to have properly initialised it when called
through save_target_globals_default_opts.

Unfortunately I'm not very familiar with the globals target switching logic so
it's not immediately clear to me where the fix should be.

If I call ira_init () after init_regs () in target_reinit () in toplev.c then
the ICE goes away, but is that the correct place to do it?