Remove hhvm builds.
Remove hhvm builds.

They don't pass due to hhvm issues and there hasn't been
much interest in hhvm lately.

ADmad/cakephp,mvdriel/cakephp,berrygoudswaard/cakephp,CakeDC/cakephp,CakeDC/cakephp,cakephp/cakephp,ndm2/cakephp,garethellis36/cakephp,davidyell/cakephp,ADmad/cakephp,ADmad/cakephp,cakephp/cakephp,mvdriel/cakephp,ADmad/cakephp,garethellis36/cakephp,petteyg/cakephp,dakota/cakephp,dakota/cakephp,petteyg/cakephp,garethellis36/cakephp,mvdriel/cakephp,tenkoma/cakephp,ndm2/cakephp,ndm2/cakephp,CakeDC/cakephp,tenkoma/cakephp,dakota/cakephp,petteyg/cakephp,CakeDC/cakephp,petteyg/cakephp,berrygoudswaard/cakephp,berrygoudswaard/cakephp,garethellis36/cakephp,mvdriel/cakephp,tenkoma/cakephp,davidyell/cakephp,cakephp/cakephp,cakephp/cakephp,dakota/cakephp,tenkoma/cakephp,ndm2/cakephp,davidyell/cakephp