[PATCH] Fix unchecked kmalloc()
fix bug in lib/list.c

in list, remove by value for the item at the end of the list doesn't
update the tail correctly
fix bug in lib/hashtable.c

in hash table, if multiple values inserted under the same key, increases
the number of items in the hash table
Merge branch 'master' of /projects/instr/14au/cse451/os161 into waitpid
waitpid implemented. bug in pid.c fixed