Maintain list tail pointers in the head node

List head nodes contain null 'prev' pointer, which we can (ab)use to maintain a
back reference to the tail pointer of the list.

While list additions are not _significantly_ improved, they are still sped up.

Original
   $ time pacman -Qo /usr/bin/wtpt
   /usr/bin/wtpt is owned by lcms 1.17-2

   real    0m3.623s
   user    0m1.883s
   sys     0m1.473s

New
   $ time pacman -Qo /usr/bin/wtpt
   /usr/bin/wtpt is owned by lcms 1.17-2

   real    0m2.006s
   user    0m0.263s
   sys     0m1.627s

Signed-off-by: Aaron Griffin <aaronmgriffin@gmail.com>

0 files changed, 0 insertions, 0 deletions