Change shm_dotruncate() so that it correctly handles cached pages that span the end of the object.  (This change is analogous to revision 1.237 of vm/vnode_pager.c.)
Change shm_dotruncate() so that it correctly handles cached pages that span
the end of the object.  (This change is analogous to revision 1.237 of
vm/vnode_pager.c.)

Discussed with: jhb

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase