Remove include_dirs from video_engine_core.gypi.
Remove include_dirs from video_engine_core.gypi.

BUG=1662
R=stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2181005

Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 7ebf0e7f44983b5e1abcf7c2db048d7a21861ef7

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