Fix guide for unshipped files in run directory

[Jonathan Liu <net147@gmail.com>]

Hi,

After 
http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=ea647cd9eebdc3e3121b84074519c4bb305adac9, 
some recipes that previously installed /var/run or files inside /var/run 
may now show QA warnings. The following is a rough guide on how to fix them.

Fix guide for unshipped files in run directory:

- If package just installs empty run directory, remove it by adding
the following to do_install_append():
rmdir "${D}${localstatedir}/run"
rmdir --ignore-fail-on-non-empty "${D}${localstatedir}"
Reference: 
http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=2aa350acca1c6b6ada6a4508611ce25e9f9576ab

- If the package creates folders inside the run directory, stop the
service, rename to something else and try starting it again. If the
service recreates the folders with the same permissions and still
starts correctly, these folders can be removed in do_install_append()
with:
rm -fr "${D}${localstatedir}/run"
Reference: 
http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=aa6408b05c5eb17b6e9fc280069f3b15eafbdab0

- If the package actually requires folders inside run directory to
start up properly and doesn't create them automatically, a file
listing them needs to be added to tmpfiles.d (for systemd) and
volatiles (for sysvinit).
Reference: 
http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=9623ccf70221f81861a42cac1eb372d77ea40ba9

Regards,
Jonathan