Suppress Memcheck:Uninitialized error when printing rtc::optional.
Suppress Memcheck:Uninitialized error when printing rtc::optional.

BUG=chromium:687087, webrtc:6822
NOTRY=True

Review-Url: https://codereview.webrtc.org/2669463003
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#16372}

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