Bug 8662 RefreshingSCPModuleInfoRegistry synchronized

Looks like (as seen on Bug 8662) there can be race conditions between
RefreshingSCPModuleInfoRegistry's updateService() and close() ... The
NPE in that bug on the "osgiReg" happens even if though that's guarded
inside a if (this.osgiReg != null), but it's during shutdown, so
presumably it JUST got set to null in close() ?  A "synchronized" on
both methods should prevent that.

Change-Id: I607092e3174c2fd0447d8548f4933624acd6a29b
Signed-off-by: Michael Vorburger <vorburger@redhat.com>