Enable -Wformat-security warning and cleanup GYP.
Enable -Wformat-security warning and cleanup GYP.

Enable the -Wformat-security and -Wformat warnings for talk/.

Remove *.def and *.h.pump files from webrtc/base/base.gyp since they're not supported by some tools.

BUG=4242
R=henrika@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/49969004

Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#9191}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 4cd6940e49e1caed059e7cc7f43a1f9232725df4

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