Minor optimization to the AutoLoader
When MediaWiki autoloading fails, we should gracefully return false.
Instead, we have been calling strtolower roughly 1,000 times in the hope
of finding a case-insensitive match.
This patch preserves the legacy case-insensitivity, but improves its
performance by approximately 100x, by storing the case-insensitive class
lookups as a static variable.
There is a new global $wgAutoloadAttemptLowercase which will switch the
behavior if desired. The default is to support case-insensitive loading.
Change-Id: Ifb12e05614a48390b730167e9d4ddcd8545db764