stdlib: cpu support for SimPoint and MAX_INSTS exit events

BaseCPU.py:
Linked "scheduleSimpointsInstStop" and "scheduleInstStopAnyThread" to
python

base.cc & base.hh:
Added scheduling functions for SimPoint and MAX_INSTS exit event.

abstract_core.py & base_cpu_core.py:
Added scheduling functions for SimPoint and MAX_INSTS exit event for stdlib
processor to access.

Jira Issue: https://gem5.atlassian.net/browse/GEM5-1259

Change-Id: I98a0f93b46a220fdb3f350d8da359c24b4d66a58
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/63153
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>

src/cpu/BaseCPU.py

@@ -71,6 +71,8 @@ class BaseCPU(ClockedObject):
         PyBindMethod("totalInsts"),
         PyBindMethod("scheduleInstStop"),
         PyBindMethod("getCurrentInstCount"),
+        PyBindMethod("scheduleSimpointsInstStop"),
+        PyBindMethod("scheduleInstStopAnyThread"),
     ]
 
     @classmethod