ITS#8321 Fix del/dupsort

When deleting a dupsort key, if other cursors pointed at that key,
set them to uninit'd, not EOF. They no longer have anything to
point at.

libraries/liblmdb/mdb.c

@@ -8252,7 +8252,7 @@ mdb_cursor_del0(MDB_cursor *mc)
 					if (m3->mc_ki[mc->mc_top] > ki)
 						m3->mc_ki[mc->mc_top]--;
 					else if (mc->mc_db->md_flags & MDB_DUPSORT)
-						m3->mc_xcursor->mx_cursor.mc_flags |= C_EOF;
+						m3->mc_xcursor->mx_cursor.mc_flags &= ~C_INITIALIZED;
 				}
 			}
 		}