Move possibly_receive() to MPI-independent section
Move possibly_receive() to MPI-independent section

The libmesh_call_mpi wrapper() should hide the actual MPI call,
and then initializing the int to 0 should make the --disable-mpi
behaviour "possibly_receive always returns false", which sounds
accurate enough.

Now I just need to test to see if this breaks horribly in the context
of the NBX parallel_sync.h when MPI is disabled.

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