Updated mediawiki/extensions
Project: mediawiki/extensions/EventLogging  95129a3ede937b8b98ce7eaa4ce6eb98fa8ba5bb
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log AccountCreation's returnto & -query params

Mediawiki's returnto and returntoquery parameters tell us where users
came from, e.g. mobile "watch".  The code doesn't log them if they're
not present.
Also remove a stray unused global.

Change-Id: Iaf6946b8cdee272697aac1e8f726f4a918c834b9