Support multiarch names.
Support multiarch names.

- follows the FHS compliant
- getLookupPrefixes improvement

Related to #329

svetlyak40wt/phpbrew,wellic/phpbrew,pinkbigmacmedia/phpbrew,phpbrew/phpbrew,kayyyy/phpbrew,mengzyou/phpbrew,viniciusferreira/phpbrew,williamn/phpbrew,konomae/phpbrew,hechunwen/phpbrew,pierredup/phpbrew,hechunwen/phpbrew,wellic/phpbrew,williamn/phpbrew,pinkbigmacmedia/phpbrew,pinkbigmacmedia/phpbrew,davidfuhr/phpbrew,viniciusferreira/phpbrew,dduca-sugarcrm/phpbrew,kayyyy/phpbrew,phpbrew/phpbrew,kayyyy/phpbrew,morozov/phpbrew,mengzyou/phpbrew,kayyyy/phpbrew,davidfuhr/phpbrew,svetlyak40wt/phpbrew,williamn/phpbrew,dduca-sugarcrm/phpbrew,konomae/phpbrew,zonuexe/phpbrew,davidfuhr/phpbrew,morozov/phpbrew,phpbrew/phpbrew,hechunwen/phpbrew,williamn/phpbrew,zonuexe/phpbrew,dduca-sugarcrm/phpbrew,mengzyou/phpbrew,davidfuhr/phpbrew,wellic/phpbrew,svetlyak40wt/phpbrew,wellic/phpbrew,mengzyou/phpbrew,konomae/phpbrew,konomae/phpbrew,pierredup/phpbrew,svetlyak40wt/phpbrew,hechunwen/phpbrew,zonuexe/phpbrew,davidfuhr/phpbrew,pierredup/phpbrew,zonuexe/phpbrew,pinkbigmacmedia/phpbrew,viniciusferreira/phpbrew,pierredup/phpbrew,dduca-sugarcrm/phpbrew,viniciusferreira/phpbrew