feat(profiles): use /etc read only variable: etc_ro

apparmor.d/groups/cron/cron

@@ -40,8 +40,8 @@ profile cron @{exec_path} {
   /etc/cron.d/{,*} r,
   /etc/crontab r,
   /etc/default/locale r,
-  /etc/environment r,
-  /etc/security/limits.d/{,**} r,
+  @{etc_ro}/environment r,
+  @{etc_ro}/security/limits.d/{,**} r,
 
   /var/spool/cron/crontabs/{,*} r,
 

apparmor.d/groups/cron/cron-exim4-base

@@ -50,7 +50,7 @@ profile cron-exim4-base @{exec_path} {
   owner @{PROC}/@{pid}/fd/ r,
         @{PROC}/1/limits r,
 
-  /etc/security/limits.d/ r,
+  @{etc_ro}/security/limits.d/ r,
 
   include if exists <local/cron-exim4-base>
 }

apparmor.d/groups/cron/cron-popularity-contest

@@ -100,7 +100,7 @@ profile cron-popularity-contest @{exec_path} {
     owner @{PROC}/@{pids}/loginuid r,
           @{PROC}/1/limits r,
 
-    /etc/security/limits.d/ r,
+    @{etc_ro}/security/limits.d/ r,
 
     /var/log/popularity-contest.new w,