improved a little the CMakeList to make it more portable
improved a little the CMakeList to make it more portable

Tatoeba/cppcms-skeleton,allan-simon/cppcms-skeleton,Tatoeba/cppcms-skeleton,tempbottle/cppcms-skeleton,allan-simon/cppcms-skeleton,tempbottle/cppcms-skeleton,allan-simon/cppcms-skeleton,tempbottle/cppcms-skeleton,Tatoeba/cppcms-skeleton,tempbottle/cppcms-skeleton,Tatoeba/cppcms-skeleton,allan-simon/cppcms-skeleton