added option for shared libprimesieve to the Makefile
added option for shared libprimesieve to the Makefile

fredwang00/primesieve,anatoliyrazin/primesieve,fredwang00/primesieve,ZahidDev/primesieve,anatoliyrazin/primesieve,kimwalisch/primesieve,tempbottle/primesieve,kimwalisch/primesieve,tempbottle/primesieve,anatoliyrazin/primesieve,fredwang00/primesieve,ZahidDev/primesieve,kimwalisch/primesieve,tempbottle/primesieve,ZahidDev/primesieve