pkgin leaks memory quadratically about pkgin

[jperkin]

Oops, thanks. Should be fixed now, I'll cut a release this week to include it.

Tested against a reasonable set of packages:

$ pkgin install texlive-collection-all-2020pre1 modular-xorg xfce4 xfce4-extras \
    netbsd-www mate py{27,36,37,38,39}-trytond php{56,73,74,80}-extensions \
    kde-workspace4 kde-runtime4
...
0 to refresh, 0 to upgrade, 2203 to install

Usage before:

  brk() allocation sizes
           value  ------------- Distribution ------------- count
           32768 |                                         0    
           65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 1992
          131072 |                                         1   
          262144 |                                         1
          524288 |                                         1
         1048576 |                                         2
         2097152 |                                         0
         
  Total bytes allocated                                     134615040
  Total number of brk() calls                                    1997

Usage after:

  brk() allocation sizes
           value  ------------- Distribution ------------- count
           32768 |                                         0
           65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@  205
          131072 |                                         1
          262144 |                                         1
          524288 |                                         1
         1048576 |                                         2
         2097152 |                                         0

  Total bytes allocated                                      17502208
  Total number of brk() calls                                     210

Annoyingly GitHub doesn't support attaching SVGs, so I've instead uploaded flamegraphs for both here:

https://us-east.manta.joyent.com/pkgsrc/public/patches/pkgin-free-flatlist/pkgin-heap-21.10.0.svg
https://us-east.manta.joyent.com/pkgsrc/public/patches/pkgin-free-flatlist/pkgin-heap-free-flatlist.svg