Revert "coll/basic: fix segmentation fault in neighborhood collectives if the degree"

This reverts commit 9c788ff9400960823637dc0eebb3a8640414fa05.
coll/basic: fix segmentation fault in neighborhood collectives if the degree
of the topology is higher than the communicator size

It is possible to have a topology degree higher than the size of the communicator.
For example, a periodic cartesian communicator on MPI_COMM_SELF. This will leave
the neighborhood collectives with a request buffer that is too small.

This commits introduces a semantic change :
from now, c_topo must be set before invoking coll_select
* comment on communicator creation in mca_topo_base_dist_graph_create(...)
* use accesors to retrieve topo info
Copy 1.8.4 release NEWS entries
Copy 1.8.4 release NEWS entries
btl/openib: send openib modex with the PMIX_GLOBAL flag
Don't release the provided opal_proc in the error path.
Merge remote-tracking branch 'origin'
Remove invalid NEWS item for 1.8.4
cleanup ugni compiler warnings
fix make dist for pmix/cray

Include file was left out of "sources" list that prevented
building for cray from dist tarball.
Merge pull request #263 from elenash/master

dstore sm component implementing shared memory database for pmix client/server communication
fix incorrect mca param registration in latest commit
Silence some warnings and remove debug output
Merge pull request #227 from ggouaillardet/rfc/coll_basic_neighbor

RFC/coll basic neighbor
Make sure initialization happens
Missed a removal from previous commit
Doh - if we can't output an entire block, then we need to adjust the number of bytes remaining to be output or else we will output duplicate bytes when next we are able to write.
enable ugni btl to work without disable-dlopen

There were mistakes in the Makefiles for the ugni btl and
mca/common/ugni that prevented the ugni btl from being
used unless one happened to set the --disable-dlopen option
on the config line.

This commit fixes this problem.
topo/base: fix uninitialized variable

this commit fixes a bug introduced by commit open-mpi/ompi@e7c59e3adbcec5693c5df0057de6c66ed2b80817