Remove libvpx suppression due to fixed bug.
Remove libvpx suppression due to fixed bug.

BUG=webm:962
R=pbos@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/45719004

Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#8742}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 12e7951bf2f2b2af34f5115bb3f6520fe1fda16b

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