Check for uninitialized audio unit in HandleInterruptionEnd.
Check for uninitialized audio unit in HandleInterruptionEnd.

This fixes a potential crash if interrupted before the audio unit has been initialized.

Bug: None
Change-Id: Ib9f5ea305c98a172f8df52af5767c8543e59701c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/136800
Reviewed-by: Henrik Andreassson <e468f06af92d21183a2a635f545ff5cefc8c8b65@webrtc.org>
Reviewed-by: Kári Helgason <79949f6d84ac41ff1f64c59fd5a554be5ff12a02@webrtc.org>
Commit-Queue: Kári Helgason <79949f6d84ac41ff1f64c59fd5a554be5ff12a02@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#27937}

TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc