Build/use constructormagic.h unconditionally.

These macros no longer collide with Chromium since they are prefixed
with RTC_.

BUG=
R=henrikg@webrtc.org

Review URL: https://codereview.webrtc.org/1477013003 .

Cr-Original-Commit-Position: refs/heads/master@{#10801}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: fd5dae395b8aa45c103671462af51aaa98cd8303
2 files changed