Remove @available annotation from async APIs, increase the requirement for non Linux platforms to the upcoming 5.5.2 (which will backport async support to the earlier Apple OSs).
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
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Description of changes:
@availableannotation from async APIs, increase the requirement for non Linux platforms to the upcoming 5.5.2 (which will backport async support to the earlier Apple OSs).By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.