Fix output of "git log --graph --boundary"

Fix output of "git log --graph --boundary"

Previously the graphing API wasn't aware of the revs->boundary flag, and
it always assumed that commits marked UNINTERESTING would not be
displayed.  As a result, the boundary commits were printed at the end of
the log output, but they didn't have any branch lines connecting them to
their children in the graph.

There was also another bug in the get_revision() code that caused
graph_update() to be called twice on the first boundary commit.  This
caused the graph API to think that a commit had been skipped, and print
a "..." line in the output.

Signed-off-by: Adam Simpkins <adam@adamsimpkins.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>