php: only deparallelize install
php: only deparallelize install

This is what I meant to do in the first place.

Signed-off-by: Jack Nagel <43386ce32af96f5c56f2a88e458cb94cebee3751@gmail.com>

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