apparmor: fix access to /etc/xml/catalog

Exporting document to .xhtml produces AppArmor deny log entry. Add
AppArmor rule for accessing /etc/xml/catalog as it is needed by libxml2.

Change-Id: If62046059c4e1d458cca895f14f7d1e3f537c527
Reviewed-on: https://gerrit.libreoffice.org/59005
Tested-by: Jenkins
Reviewed-by: Rene Engelhard <rene@debian.org>

sysui/desktop/apparmor/program.soffice.bin

@@ -107,6 +107,7 @@ profile libreoffice-soffice INSTDIR-program/soffice.bin {
   /etc/libreoffice/**                   r,
 
   /etc/cups/ppd/*.ppd                   r,
+  /etc/xml/catalog                      r, #exporting to .xhtml, for libxml2
   /proc/*/status                        r,
 
   owner @{HOME}/.config/libreoffice{,dev}/** rwk,