Fix random "personality" corruption when linking against lxc 6

When using python3-lxc with liblxc from lxc 6.0.x, we could observe
random systemd startup failures on containers.

systemd will report this on startup when the corruption hit:
"Warning! Reported kernel version 2.6.74-300.fc42.x86_64 is older than systemd's required baseline kernel version 4.15. Your mileage may vary."

Some systemd services fail to start properly, including systemd-journald.

The root problem is that other lxc library code unexpectedly calls into
lxc_config_parse_arch() from python3-lxc instead of the function from liblxc.

The function signature of lxc_config_parse_arch() changed throughout the years
and the second "persona" pointer argument was added. The older python3-lxc copy
of the function would not initialize the provided memory location of "persona".
It will therefore contain a random value.

Additionally the symbol visibility of liblxc's lxc_config_parse_arch()
changed with this commit in lxc 6.0:

******************************************
commit 42eeffcb05c468fd7b3a90eeda4a3abe9f26844b
AuthorDate: Sun Feb 18 15:43:20 2024 +0100

    confile: unhide lxc_config_parse_arch() helper

    Looks safe enough to be available for liblxc users.
******************************************

This results in two symbols with the same name and
the python3-lxc symbol takes precedence.

Fix the issue by making the function static in python3-lxc,
so python3-lxc stays compatible with lxc 5.x and 6.x.

A future python3-lxc version might remove the local function
and use lxc_config_parse_arch() from liblxc 6.0 and later.

Side quest: Even though lxc 5.0 already has the "persona" function argument in
lxc_config_parse_arch() since 7c43fa56e70c65607f63dec8ff5a9682a3091ab2 (from 2021),
it is not affected since the symbol visibility is still hidden.

Signed-off-by: Thomas Jarosch <thomas.jarosch@intra2net.com>

Author: thomasjfox

lxc.c

@@ -81,7 +81,7 @@ static int lxc_wait_for_pid_status(pid_t pid)
 }
 
 /* Copied from lxc/confile.c, with HAVE_SYS_PERSONALITY_H check removed */
-signed long lxc_config_parse_arch(const char *arch)
+static signed long lxc_config_parse_arch(const char *arch)
 {
     struct per_name {
         char *name;