Medtronic Inc. (MDT), the globe-spanning medical device maker founded in a Minneapolis garage in 1949, is poised to become the biggest company yet to escape the U.S. tax system by shifting its incorporation abroad. Medtronic said yesterday it plans to take a legal address in tax-friendly Ireland as part of a $42.9 billion takeover of Covidien Plc. (COV) Although Covidien is run from Mansfield, Massachusetts, it’s been incorporated in Ireland since 2009.