Enable logging for Mac by default on debug builds.
Enable logging for Mac by default on debug builds.

Was previously using the wrong preprocessor define (DEBUG vs _DEBUG).

Review URL: https://codereview.webrtc.org/1361173002

Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#10061}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 59e72ab49b05febceffa38c815e79d690305c95f

sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc