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
btl/vader: use FRAG_ALLOC_USER when single_copy_mechanism is VADER_NONE
OSHMEM: sshmem verbs: fix shared_mr detection

It seems that 5ce2f1006762ef908b2960df5b93dc7532f8e448
changed default flag values but it did not modify detection code.
NEWS: sync with 1.8.4 bullets
NEWS: whitespace cleanup; no content changes
OpenMPI.3in: remove trailing blank lines; no content changes