Also, registering a weak-pointer to close the module that
was just made as resident is pointless.

Closing the library will interfere badly as the glib types cannot be
unregistered. We must leak the library handle.

Fixes: 3adf782ab556e343a34f0153f50f72a2fd0ee791

On s390 size_t is an unsigned long, not an unsigned int. They both are
of the same size and can be cast to each other safely, but the compiler
still seems unhappy about incompatible pointers.

https://github.com/systemd/systemd/pull/3147

It can return NULL and makes Coverity upset:

CID 75369 (#1 of 1): Dereference null return value (NULL_RETURNS)
4.  dereference: Dereferencing a null pointer ret.

CID 76722 (#1 of 1): Logically dead code (DEADCODE)
dead_error_line: Execution cannot reach this statement:
g_set_error(error, nm_setti....

CID 99747 (#1 of 1): Missing varargs init or cleanup (VARARGS)
13.  missing_va_end: va_end was not called for ap.

We might receive the update of the device state to FAILED when the
active connection is still in ACTIVATING. Handle this case properly.

It is recomended to include <config.h> with angle brackets [1].

Note, that usually we don't include <config.h> directly, except in
two places we have to (because there we include conflicting libraries
that must be included before "nm-default.h").
In that case, define __CONFIG_H__ which is used as include guard around
<config.h> by "nm-default.h".

[1] https://www.gnu.org/software/autoconf/manual/autoconf-2.66/html_node/Configuration-Headers.html