_platform: Don't use psutil.Process.cpu_affinity on unsupported platforms
psutil.Process.cpu_affinity
is not available on many non-Linux
platforms, like AIX and Solaris. We already have such a case with Darwin
where we need to resort to using os.cpu_count()
.
Rather than adding more subclasses and overrides, add that logic as a
fallback in the main Process
class. os.cpu_count()
should generally
always be available, so hopefully we will only need to override this in
future too much or at all.
Fixes #1244 (closed).