Revert "Require libxml2 to fix OS X 10.11 issues"
Revert "Require libxml2 to fix OS X 10.11 issues"

This reverts commit 0ba8cfa899cb32777a84c7b7e80e1c6c9893dfff.

philcook/homebrew-php,ablyler/homebrew-php,mkalkbrenner/homebrew-php,dguyon/homebrew-php,TomK/homebrew-php