Allow umask to be configurable.
Being able to set the umask via an rc variable is useful when setting:
security.bsd.unprivileged_read_msgbuf=0
As it allows a user to configure:
dmesg_umask="066"
Without modifying the rc script, and preventing the contents of the
$dmesg_file (/var/run/dmesg.boot) from being publicly readable.
PR: 272552
Reviewed by: netchild
MFC after: 2 days
Differential Revision: https://reviews.freebsd.org/D53169
Jose Luis Duran
edadbc6ee9