Refactor: libcrmservice: Defunctionize create_world_readable()

I think this is clearer. The glibc doc also recommends fchmod() over
umask():
https://www.gnu.org/software/libc/manual/html_node/Setting-Permissions.html

It shouldn't matter in our case. umask() isn't thread-safe, but
Pacemaker is single-threaded. Still, setting the permissions explicitly
seems clearer.

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>