Use string::clear() instead of string::erase().
Use string::clear() instead of string::erase().

The original code was apparently a workaround for an older compiler that
we no longer support anyway.

hrittich/libmesh,jwpeterson/libmesh,dschwen/libmesh,pbauman/libmesh,roystgnr/libmesh,dschwen/libmesh,capitalaslash/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,dschwen/libmesh,roystgnr/libmesh,pbauman/libmesh,pbauman/libmesh,jwpeterson/libmesh,90jrong/libmesh,roystgnr/libmesh,BalticPinguin/libmesh,hrittich/libmesh,90jrong/libmesh,roystgnr/libmesh,jwpeterson/libmesh,libMesh/libmesh,libMesh/libmesh,jwpeterson/libmesh,BalticPinguin/libmesh,dschwen/libmesh,libMesh/libmesh,jwpeterson/libmesh,90jrong/libmesh,dschwen/libmesh,BalticPinguin/libmesh,hrittich/libmesh,90jrong/libmesh,jwpeterson/libmesh,capitalaslash/libmesh,libMesh/libmesh,capitalaslash/libmesh,hrittich/libmesh,capitalaslash/libmesh,dschwen/libmesh,90jrong/libmesh,BalticPinguin/libmesh,libMesh/libmesh,dschwen/libmesh,roystgnr/libmesh,roystgnr/libmesh,90jrong/libmesh,90jrong/libmesh,pbauman/libmesh,pbauman/libmesh,libMesh/libmesh,hrittich/libmesh,hrittich/libmesh,BalticPinguin/libmesh,hrittich/libmesh,jwpeterson/libmesh,pbauman/libmesh,90jrong/libmesh,hrittich/libmesh,libMesh/libmesh,pbauman/libmesh,BalticPinguin/libmesh,pbauman/libmesh,roystgnr/libmesh,dschwen/libmesh,pbauman/libmesh,hrittich/libmesh,capitalaslash/libmesh,jwpeterson/libmesh,capitalaslash/libmesh,libMesh/libmesh,capitalaslash/libmesh,90jrong/libmesh,capitalaslash/libmesh,roystgnr/libmesh