Changes from pkg 1.10.99.4 to 1.10.99.5

- pkg clean is now happy if the cache dir non existing

- 410.pkg-audit now uses anticongestion on freebsd 12

- fix pkg install -r foo if foo is a disabled repository

- fix elf handling on non FreeBSD

- fix support for platforms without AT_SYMLINK_NOFOLLOW

- fix dropping privileges on Linux

- fix build with recent libbsd

- fix duplicate pkg registration overwriting the existing pkg

- better ABI name on linux

- lots of changes in internal API to use fd when possible

- removed option: pkg repo -L