Clarification of RtpPacket constructor in comment.
Clarification of RtpPacket constructor in comment.

See also b/175210069 for more context.

Bug: None
Change-Id: I06e9848028c0f11362db373af54b42cbc67aee77
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/198780
Reviewed-by: Danil Chapovalov <55de8d9c2b5977da2dd48f967f21f9d606b172a5@webrtc.org>
Commit-Queue: Henrik Grunell <2ba6955c3c55a5b485523ca0a5f0d83995af4be8@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#32874}

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