Improve memory usage resolving dependencies II
Improve memory usage resolving dependencies II

Optimize `rulesByHash` in `Composer\DependencyResolver\RuleSet` to only
use an array with the second element, event with very low probability.

SpacePossum/composer,dzuelke/composer,composer/composer,johnstevenson/composer,balbuf/composer,stof/composer,hirak/composer,staabm/composer,fabiang/composer,alcohol/composer,fabpot/composer,gencer/composer,stefangr/composer,milleruk/composer,floverdevel/composer,nicolas-grekas/composer,pierredup/composer,curry684/composer,slbmeh/composer,vdm-io/composer,andrerom/composer,erasys/composer,remicollet/composer,localheinz/composer,naderman/composer