apply more comments from jbeich

Apply comments from jbeich

ping?

The patch needs to be rebased, at least for math/R.

Does this patch include r527876, or is that commit independent of this patch ?

In D23984#527482, @jrm wrote:

The build fails on 11.3 i386.

In file included from ../../base/profiler/stack_copier_suspend.cc:7:
In file included from ../../base/profiler/metadata_recorder.h:14:
In file included from ../../base/synchronization/lock.h:11:
../../base/synchronization/lock_impl.h:71:12: warning: releasing mutex 'native_handle_' that was not held [-Wthread-safety-analysis]
  int rv = pthread_mutex_unlock(&native_handle_);
           ^
../../base/profiler/stack_copier_suspend.cc:51:14: error: use of undeclared identifier 'RegisterContextStackPointer'
    bottom = RegisterContextStackPointer(thread_context);
             ^
1 warning and 1 error generated.

Here is the full build log: http://pkg.awarnach.mathstat.dal.ca/data/11i386-default/2020-03-06_23h58m22s/logs/errors/chromium-80.0.3987.132.log

Close after commit (r524409)