Add lowercase variants to the autoloader for legacy history blob classes

Blobs in the text table created by MediaWiki <1.5 running on PHP 4 had class
names coerced to lowercase. In order to succcessfully resolve these class
names, the autoloader creates a copy of the autoload class array with
lowercased keys, which is pretty inefficient. So instead, make sure the
auto-generated autoload map contains lowercase variants for these specific
classes.

Bug: T166759
Change-Id: I6d751ef516e936e04c056d70a1ecd17960a39ceb