This is a followup to d7113bb655 and
e3358a831e.
* gnu/services/base.scm (syslog-service-type): Change 'start' method to set
umask using the #:file-creation-mask parameter of
'make-forkexec-constructor' introduced in version 0.8.0 of the Shepherd.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>