gen_autofdo_event.py was stumbling on models with stepping so
I updated the script to handle this case similar to the code in
c6a5f63aed/event_download.py
The second change was to tolerate cases when the CPU supports PEBS but the
perf command with /p fails. This can happen in, e.g., a virtual machine.
I regenerated gcc-auto-profile using the updated script.
contrib/ChangeLog:
* gen_autofdo_event.py: handle stepping, non-working PEBS
gcc/ChangeLog:
* config/i386/gcc-auto-profile: regenerate
