Don't use explicit constructor in copy-initialization.
Don't use explicit constructor in copy-initialization.

This aligns "GetTransceivers" with "GetSenders" / "GetReceivers" and
fixes a compilation error if an older libstdc++ from the system is used.

Bug: None
Change-Id: I1cab00549b28c24c2bfdfcef17302db2c70a2fce
Reviewed-on: https://webrtc-review.googlesource.com/90861
Commit-Queue: Joachim Bauch <96bf565d373a275ea07323a22ba8d332016bbe29@webrtc.org>
Reviewed-by: Henrik Boström <106ab6647ddadbf38d6259e9d5ec4de77fa52c00@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#24128}
TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc