[3.13] gh-128146: Exclude os/log.h import on older macOS versions. (GH-128165) (#128575)

gh-128146: Exclude os/log.h import on older macOS versions. (GH-128165)

Reworks the handling of Apple system log handling to account for older macOS
versions that don't provide os-log.
(cherry picked from commit e837a1f71e832ce8f551a6fac05e346f654457e0)

Co-authored-by: Russell Keith-Magee <russell@keith-magee.com>