fix failing test of rsyslog::snippet

Author: saz

spec/defines/rsyslog_snippet_spec.rb

@@ -12,6 +12,9 @@
       let :facts do
         facts
       end
+      let :pre_condition do
+        'include rsyslog'
+      end
 
       rsyslog_d = case facts[:os]['family']
                   when 'FreeBSD'