third_party: Add OWNERS for speex library.
third_party: Add OWNERS for speex library.

For more informating see
https://www.chromium.org/developers/adding-3rd-party-libraries#TOC-Add-OWNERS

chromium-dev discussion was:
https://groups.google.com/a/chromium.org/d/topic/chromium-dev/tBiPPpqfku4/discussion

BUG=None
R=philipj@opera.com, tommi@chromium.org

Review URL: https://codereview.chromium.org/1223413004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#338252}

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