Move ringid store and load from totem library

Functions for storing and loading ring id was in the totem library. This
causes problem, what to do when it's impossible to load or store ring
id. Easy solution seemed to be assert, but sadly this makes hard for
user to find out what happened (because corosync was just aborted and
logsys didn't flush)

Solution is to move these functions to main.c, where is much easier to
handle error.

Patch also introduces get_run_dir function.

Run dir (LOCALSTATEDIR/lib/corosync) was hardcoded thru whole codebase.
Totemsrp was trying to create and chdir into it, but also
takes into account environment variable COROSYNC_RUN_DIR creating
inconsistency.

get_run_dir correctly returns COROSYNC_RUN_DIR (when set) or
LOCALSTATEDIR/lib/corosync. This is now used by all functions instead of
hardcoded string.

All occurrences of mkdir/chdir are removed from totemsrp and chdir is
now called in main function. Mkdir call is completely removed, because
it was not used anyway (check in main.c was called before totemsrp
init, so mkdir was never called) and also make install and/or package
system should take care of creating this directory with correct
permissions/context.

This makes libtotem free of any file system operations.

(backported from master d310b251c3ba5e92c7ca1b8f6f8197d71141a8d6 and
da46ecfc3087de97ad9a76fe6a156f10170503a2)

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Christine Caulfield <ccaulfie@redhat.com>