Don't override curve preferences in BoringSSL.
Don't override curve preferences in BoringSSL.

BoringSSL has since fixed OpenSSL's API wart and can do ECDHE by default as a server. Notably, removing this call means that X25519 may be used as either client or server.

R=torbjorng@webrtc.org
TBR=juberti@webrtc.org

BUG=webrtc:5674

Review URL: https://codereview.webrtc.org/1823213002 .

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#12120}

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