Remove linux makefile, so that it can be re-added as text per .gitattributes
Remove linux makefile, so that it can be re-added as text per .gitattributes

EricWhiteDev/Open-XML-SDK,EricWhiteDev/Open-XML-SDK,ThomasBarnekow/Open-XML-SDK,tomjebo/Open-XML-SDK,mimisasouvanh/Open-XML-SDK,OfficeDev/Open-XML-SDK,tarunchopra/Open-XML-SDK,ClareMSYanGit/Open-XML-SDK