Remove unused fields in pfs_process structure.

c2640f2b removed the code that used them.
using hash table to de-duplicate namelist
add stderr redirection to system function
move special caller checking procedure from pfs_package_create.c into pfs_table.cc
add -Wall -pg into configure
hardcode copy degree
modify comments about special_caller
check the state of namelist_table instread of namelist_file
add test specification and notes for packaging utility
let parrot_package_create be responsible for `sort -u special_files`

allow chroot_package_run and package_package_run both have the right to sort the special_files has side effect:
the sorted special_files of chroot_package_run can not be accessed by parrot_package_run.
remove -Wall -pg from configure