Call $wgContLang->findVariantLink() in {{PAGESINCATEGORY: }}

Corrects inconsistent return value for number of pages in a
category when language variants are in use.

Change-Id: I27668ba348c45bc34b264f8771e91e58a9920552
Merge "Call $wgContLang->findVariantLink() in {{PAGESINCATEGORY: }}"