Added an empty member to the union of rtc::Optional, so that it is always initializable.
Added an empty member to the union of rtc::Optional, so that it is always initializable.

Added notry due to flaky android_dbg bot.

NOTRY=true
BUG=webrtc:6033

Review-Url: https://codereview.webrtc.org/2090223003
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#13343}

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