BulletSim: fix problem of a null reference exception on shutdown if there were linksets in the region.
BulletSim: fix problem of a null reference exception on shutdown if there were linksets in the region.

M-O-S-E-S/opensim,justinccdev/opensim,Michelle-Argus/ArribasimExtract,BogusCurry/arribasim-dev,M-O-S-E-S/opensim,rryk/omp-server,TomDataworks/opensim,M-O-S-E-S/opensim,EriHoss/OpenSim_0.8.2.0_Dev_LibLSLCC,justinccdev/opensim,ft-/arribasim-dev-tests,Michelle-Argus/ArribasimExtract,Michelle-Argus/ArribasimExtract,Michelle-Argus/ArribasimExtract,ft-/arribasim-dev-extras,M-O-S-E-S/opensim,BogusCurry/arribasim-dev,ft-/opensim-optimizations-wip-tests,RavenB/opensim,ft-/opensim-optimizations-wip-extras,Michelle-Argus/ArribasimExtract,OpenSimian/opensimulator,EriHoss/OpenSim_0.8.2.0_Dev_LibLSLCC,ft-/opensim-optimizations-wip,ft-/opensim-optimizations-wip-tests,ft-/arribasim-dev-tests,bravelittlescientist/opensim-performance,ft-/arribasim-dev-extras,RavenB/opensim,rryk/omp-server,bravelittlescientist/opensim-performance,TomDataworks/opensim,justinccdev/opensim,ft-/arribasim-dev-extras,ft-/arribasim-dev-tests,BogusCurry/arribasim-dev,ft-/opensim-optimizations-wip-extras,Michelle-Argus/ArribasimExtract,RavenB/opensim,TomDataworks/opensim,BogusCurry/arribasim-dev,ft-/opensim-optimizations-wip,RavenB/opensim,BogusCurry/arribasim-dev,justinccdev/opensim,bravelittlescientist/opensim-performance,OpenSimian/opensimulator,rryk/omp-server,rryk/omp-server,bravelittlescientist/opensim-performance,QuillLittlefeather/opensim-1,justinccdev/opensim,ft-/arribasim-dev-extras,QuillLittlefeather/opensim-1,OpenSimian/opensimulator,RavenB/opensim,ft-/arribasim-dev-tests,QuillLittlefeather/opensim-1,bravelittlescientist/opensim-performance,EriHoss/OpenSim_0.8.2.0_Dev_LibLSLCC,M-O-S-E-S/opensim,QuillLittlefeather/opensim-1,BogusCurry/arribasim-dev,ft-/opensim-optimizations-wip-extras,QuillLittlefeather/opensim-1,OpenSimian/opensimulator,ft-/arribasim-dev-tests,OpenSimian/opensimulator,ft-/opensim-optimizations-wip-extras,rryk/omp-server,ft-/arribasim-dev-extras,TomDataworks/opensim,EriHoss/OpenSim_0.8.2.0_Dev_LibLSLCC,TomDataworks/opensim,RavenB/opensim,ft-/opensim-optimizations-wip,ft-/arribasim-dev-extras,ft-/opensim-optimizations-wip-tests,OpenSimian/opensimulator,justinccdev/opensim,EriHoss/OpenSim_0.8.2.0_Dev_LibLSLCC,ft-/opensim-optimizations-wip-tests,RavenB/opensim,TomDataworks/opensim,EriHoss/OpenSim_0.8.2.0_Dev_LibLSLCC,OpenSimian/opensimulator,TomDataworks/opensim,ft-/opensim-optimizations-wip,ft-/opensim-optimizations-wip-extras,EriHoss/OpenSim_0.8.2.0_Dev_LibLSLCC,ft-/opensim-optimizations-wip-tests,M-O-S-E-S/opensim,QuillLittlefeather/opensim-1,M-O-S-E-S/opensim,QuillLittlefeather/opensim-1,bravelittlescientist/opensim-performance,rryk/omp-server,ft-/arribasim-dev-tests