Roll external/skia 71e434dc9..32d8cce07 (1 commits)

https://skia.googlesource.com/skia.git/+log/71e434dc9..32d8cce07

2019-02-03 reed@google.com Revert "Revert "remove legacy forward declares""

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Change-Id: I069b065947c2462bd06d1013d48cfe2f670dc9db
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