Log Message:
pkgtools/pkgchkxx: Update to 0.2

* Performance improvement: `pkgchkxx -s` no longer invokes `make update
  CLEANDEPENDS=yes` but now uses `make update
  DEPENDS_TARGET='package-install clean'`.
* Performance improvement: `pkgrrxx` by default now removes working
  directories directly instead of running `make clean`, which is slow. You
  can disable this optimization with a configure option
  `--disable-fast-clean`.
* Performance improvement: Tools now use `posix_spawn(3)` on platforms
  where it exists, and fall back to `fork` & `exec` where it doesn't.
* `pkgrrxx` now shows the number of entries in each non-empty TODO list, to
  give the user some clue about the time it's going to take.
* Fixed an issue where `RR> ` could be printed twice depending on how the
  C++ compiler optimized the code.