check_periodic_bcs bool for efficiency
check_periodic_bcs bool for efficiency

If we've got a _periodic_bcs set but it's an empty set then we still
can skip all of the PBC rigamarole.

giorgiobornia/libmesh,roystgnr/libmesh,90jrong/libmesh,benkirk/libmesh,svallaghe/libmesh,balborian/libmesh,giorgiobornia/libmesh,90jrong/libmesh,vikramvgarg/libmesh,benkirk/libmesh,vikramvgarg/libmesh,svallaghe/libmesh,90jrong/libmesh,vikramvgarg/libmesh,friedmud/libmesh,friedmud/libmesh,balborian/libmesh,balborian/libmesh,pbauman/libmesh,capitalaslash/libmesh,friedmud/libmesh,BalticPinguin/libmesh,friedmud/libmesh,jwpeterson/libmesh,benkirk/libmesh,libMesh/libmesh,giorgiobornia/libmesh,roystgnr/libmesh,libMesh/libmesh,90jrong/libmesh,jwpeterson/libmesh,hrittich/libmesh,svallaghe/libmesh,roystgnr/libmesh,capitalaslash/libmesh,90jrong/libmesh,capitalaslash/libmesh,vikramvgarg/libmesh,hrittich/libmesh,dschwen/libmesh,roystgnr/libmesh,balborian/libmesh,benkirk/libmesh,pbauman/libmesh,capitalaslash/libmesh,vikramvgarg/libmesh,hrittich/libmesh,roystgnr/libmesh,benkirk/libmesh,jwpeterson/libmesh,libMesh/libmesh,BalticPinguin/libmesh,90jrong/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,hrittich/libmesh,svallaghe/libmesh,svallaghe/libmesh,friedmud/libmesh,balborian/libmesh,90jrong/libmesh,90jrong/libmesh,pbauman/libmesh,friedmud/libmesh,libMesh/libmesh,friedmud/libmesh,roystgnr/libmesh,giorgiobornia/libmesh,giorgiobornia/libmesh,dschwen/libmesh,benkirk/libmesh,friedmud/libmesh,capitalaslash/libmesh,vikramvgarg/libmesh,giorgiobornia/libmesh,pbauman/libmesh,pbauman/libmesh,roystgnr/libmesh,dschwen/libmesh,jwpeterson/libmesh,benkirk/libmesh,pbauman/libmesh,benkirk/libmesh,jwpeterson/libmesh,giorgiobornia/libmesh,vikramvgarg/libmesh,libMesh/libmesh,svallaghe/libmesh,capitalaslash/libmesh,BalticPinguin/libmesh,pbauman/libmesh,giorgiobornia/libmesh,dschwen/libmesh,friedmud/libmesh,BalticPinguin/libmesh,balborian/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,dschwen/libmesh,hrittich/libmesh,roystgnr/libmesh,balborian/libmesh,giorgiobornia/libmesh,dschwen/libmesh,svallaghe/libmesh,balborian/libmesh,libMesh/libmesh,svallaghe/libmesh,90jrong/libmesh,pbauman/libmesh,balborian/libmesh,dschwen/libmesh,vikramvgarg/libmesh,hrittich/libmesh,BalticPinguin/libmesh,capitalaslash/libmesh,hrittich/libmesh,pbauman/libmesh,svallaghe/libmesh,vikramvgarg/libmesh,capitalaslash/libmesh,balborian/libmesh,hrittich/libmesh,libMesh/libmesh,benkirk/libmesh,BalticPinguin/libmesh,hrittich/libmesh,libMesh/libmesh,dschwen/libmesh,jwpeterson/libmesh