Call into z_thread_usage_stop() before ISR entry to avoid including
interrupt handling totals in thread usage stats.
Note that this hook is after the register save and stack swap has
happened, so it still incldues some overhead. But calling out from
the interrupted stack on Xtensa gets really, really hairy due to the
weird intermediate states we leverage (once we've saved enough context
to make a C call safely, we've lost the ability to use register
windows per the C ABI!).
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
884f1bf39d