Fix includedir directive in krb5.conf template

We did not have the includedir directory with a trailing slash which made
rpm update add a redundant line.

https://fedorahosted.org/freeipa/ticket/3132

install/share/krb5.conf.template

@@ -1,4 +1,4 @@
-includedir /var/lib/sss/pubconf/krb5.include.d
+includedir /var/lib/sss/pubconf/krb5.include.d/
 
 [logging]
  default = FILE:/var/log/krb5libs.log