core: do not crash setting the log level before the process table exists

[Lt-Flash]

What

set_proc_log_level() and reset_proc_log_level() segfault when called from a module's mod_init().

Root cause

init_modules() runs several steps before init_multi_proc_support(), so the process table is still NULL while every module's mod_init() executes — and the setter writes through it unconditionally:

void __set_proc_log_level(int proc_idx, int level)
{
	pt[proc_idx].log_level = level;      /* pt == NULL during mod_init() */
}

reset_proc_log_level() fails the same way one level down: default_log_level is a static pointer that init_log_level() has not filled in yet, so it dereferences NULL.

Why it is worth guarding

Temporarily lowering the log level around a call that is expected to fail is the natural way for a module to keep a benign startup error out of its output — and the API gives no hint that it is unusable at exactly the point most modules would reach for it. The failure is a hard crash at startup, not a diagnostic.

The fix

Guards each affected setter. Where the intent can still be honoured it is, rather than silently dropping the request:

• __set_proc_log_level() — log_level already points at the static holder before init_log_level() runs, and there is only one process at that stage, so the level is applied through it.
• reset_proc_log_level() — restores the value logging started with (log_level_holder).
• __set_proc_default_log_level() — updates that same holder.
• set_global_log_level() — additionally guards log_level_global, which init_log_level() allocates. Before that, counted_max_processes is 0 so its loop is a no-op and the shared value does not exist, so it applies the level to the current process instead.
• suppress_proc_log_event() / reset_proc_log_event() — return early; the event consumer they guard is not running yet either.

No behaviour changes once the process table exists — every guard is a NULL check on state that is non-NULL from init_multi_proc_support() onward.

Testing

A/B tested with a module calling set_proc_log_level() followed by reset_proc_log_level() from its mod_init(): the same module segfaults on an unpatched core and starts normally on a patched one.