Allow slavesolver to execute in parallel.


git-svn-id: svn://svn.code.sf.net/p/elmerfem/code/trunk@6802 04224531-1f84-46d8-96ce-875b9e37dce3
small safety fix..


git-svn-id: svn://svn.code.sf.net/p/elmerfem/code/trunk@6803 04224531-1f84-46d8-96ce-875b9e37dce3