remove ompi comm related constructs from ugni btl

There were remaining references to size of MPI_COMM_WORLD,
etc. in ugni btl which prevented building of opal library
following btl move to opal.

Eventually another mechanism will need to be found for
providing hints to BTLs about how to setup internal
resources relevant to max. number possible endpoints, etc.

Conflicts:
	opal/mca/btl/ugni/btl_ugni_component.c