sstate-sysroot-cruft.sh: Improve to use it from CI

sstate-sysroot-cruft.sh: Improve to use it from CI

* strip tmpdir prefix, so that we have shorter paths which aren't
  builder specific
* use '#' for regexp delimiter so that we don't need to prefix
  forward slashes in paths
* extend default whitelist to cover typical cases
* add parameter for external whitelist file
* use number of found paths as return code, so that CI can easily
  report error when new untracked files are found
* use .txt suffix for all output files, so that they can be easily
  viewed in browser
* add populate_sysroot task, because somewhere between dora and daisy
  the populate-sysroot files in sstate-control were renamed to have
  underscore instead of dash
* only few entries not covered by this default whitelist were found
  in world build (but I'll leave these for people to whitelist, because
  they are not generated in most builds)
  * [^/]*/home/builder
    home directory from meta/recipes-graphics/builder/builder_0.1.bb
  * [^/]*/usr/src/kernel/patches
  * [^/]*/usr/lib/gdk-pixbuf-2.0/.*/loaders.cache
    3 places are using this, not sure which one creates it
    meta/recipes-gnome/gdk-pixbuf/gdk-pixbuf_2.30.8.bb:
      GDK_PIXBUF_MODULE_FILE=${STAGING_LIBDIR_NATIVE}/gdk-pixbuf-2.0/${LIBV}/loaders.cache
    meta/recipes-gnome/gtk+/gtk-update-icon-cache-native_3.4.4.bb:
      GDK_PIXBUF_MODULE_FILE=${STAGING_LIBDIR_NATIVE}/gdk-pixbuf-2.0/2.10.0/loaders.cache
    scripts/postinst-intercepts/update_pixbuf_cache:
      >$GDK_PIXBUF_MODULEDIR/../loaders.cache && \
      sed -i -e "s:$D::g" $GDK_PIXBUF_MODULEDIR/../loaders.cache

(From OE-Core rev: b1bfec63949e16abe8c11c34530dfbfb176c04cd)

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>