Merge tunable: add int variable

This PR only adds the digit `@{d}` and integer `@{int}` variables.

It provides two improvements from the use of the `[0-9]*` glob:
- security: the glob means "a digit followed by anything but `/`", whereas `@{int}` means "up to 10 digits"
Next to the
- stability: using glob in path with `x` can expose to path conflict, removing the glob fixed a lot of issues.

These variables are used by a lot of abstractions that could be upstream here from apparmor.d (PR will follow). It is an import from 33681e14f2/apparmor.d/tunables/multiarch.d/system where other similar variables are in use: `@{hex}`, `@{rand}`, `@{word}`, `@{u8}`, `@{u16}`, `@{u64}`, `@{int2}...@{int64}` ...
They also all could be upstreamed here.

MR: https://gitlab.com/apparmor/apparmor/-/merge_requests/1544
Approved-by: John Johansen <john@jjmx.net>
Merged-by: John Johansen <john@jjmx.net>

profiles/apparmor.d/tunables/global

@@ -17,6 +17,7 @@ include <tunables/multiarch>
 include <tunables/proc>
 include <tunables/alias>
 include <tunables/kernelvars>
+include <tunables/system>
 include <tunables/xdg-user-dirs>
 include <tunables/share>
 include <tunables/etc>

profiles/apparmor.d/tunables/system

@@ -0,0 +1,17 @@
+# ------------------------------------------------------------------
+#
+#    Copyright (C) 2025 Alexandre Pujol <alexandre@pujol.io>
+#
+#    This program is free software; you can redistribute it and/or
+#    modify it under the terms of version 2 of the GNU General Public
+#    License published by the Free Software Foundation.
+#
+# ------------------------------------------------------------------
+
+# Any digit
+@{d}=[0-9]
+
+# Integer up to 10 digits (0-9999999999)
+@{int}=@{d}{@{d},}{@{d},}{@{d},}{@{d},}{@{d},}{@{d},}{@{d},}{@{d},}{@{d},}
+
+include if exists <tunables/system.d>