Track rename of async_io_test to posix_async_io_test

This was renamed in:

https://android-review.googlesource.com/c/platform/frameworks/av/+/400388

Test: m nothing, no longer a warning about unknown module async_io_test
Change-Id: Iae72ec743a679a01fcb94cc36ec3372560729883
Merged-In: Iae72ec743a679a01fcb94cc36ec3372560729883