Restore process name via prctl on restart.

git-svn-id: svn://svn.code.sf.net/p/dmtcp/code/trunk@2460 ba6dc0ae-232f-0410-883f-9ebac64fc565
Replace fscanf with fread/strtoull to fix compiler warning.

git-svn-id: svn://svn.code.sf.net/p/dmtcp/code/trunk@2461 ba6dc0ae-232f-0410-883f-9ebac64fc565