Makefile.am:3462: warning: $(src_devices_bluetooth_libnm_device_plugin_bluetooth_la_OBJECTS) was already defined in condition TRUE, which includes condition WITH_MODEM_MANAGER_1 ...
 Makefile.am:960: ... '$(src_devices_bluetooth_libnm_device_plugin_bluetooth_la_OBJECTS)' previously defined here

Fixes: 878d4963ed7e ('bluetooth/tests: add "nm-bt-test helper" program for manual testing of bluetooth code')

This is a complete refactoring of the bluetooth code.

Now that BlueZ 4 support was dropped, the separation of NMBluezManager
and NMBluez5Manager makes no sense. They should be merged.

At that point, notice that BlueZ 5's D-Bus API is fully centered around
D-Bus's ObjectManager interface. Using that interface, we basically only
call GetManagedObjects() once and register to InterfacesAdded,
InterfacesRemoved and PropertiesChanged signals. There is no need to
fetch individual properties ever.

Note how NMBluezDevice used to query the D-Bus properties itself by
creating a GDBusProxy. This is redundant, because when using the ObjectManager
interfaces, we have all information already.

Instead, let NMBluezManager basically become the client-side cache of
all of BlueZ's ObjectManager interface. NMBluezDevice was mostly concerned
about caching the D-Bus interface's state, tracking suitable profiles
(pan_connection), and moderate between bluez and NMDeviceBt.
These tasks don't get simpler by moving them to a seprate file. Let them
also be handled by NMBluezManager.

I mean, just look how it was previously: NMBluez5Manager registers to
ObjectManager interface and sees a device appearing. It creates a
NMBluezDevice object and registers to its "initialized" and
"notify:usable" signal. In the meantime, NMBluezDevice fetches the
relevant information from D-Bus (although it was already present in the
data provided by the ObjectManager) and eventually emits these usable
and initialized signals.
Then, NMBlue5Manager emits a "bdaddr-added" signal, for which NMBluezManager
creates the NMDeviceBt instance. NMBluezManager, NMBluez5Manager and
NMBluezDevice are strongly cooperating to the point that it is simpler
to merge them.

This is not mere refactoring. This patch aims to make everything
asynchronously and always cancellable. Also, it aims to fix races
and inconsistencies of the state.

- Registering to a NAP server now waits for the response and delays
  activation of the NMDeviceBridge accordingly.

- For NAP connections we now watch the bnep0 interface in platform, and tear
  down the device when it goes away. Bluez doesn't send us a notification
  on D-Bus in that case.

- Rework establishing a DUN connection. It no longer uses blocking
  connect() and does not block until rfcomm device appears. It's
  all async now. It also watches the rfcomm file descriptor for
  POLLERR/POLLHUP to notice disconnect.

- drop nm_device_factory_emit_component_added() and instead let
  NMDeviceBt directly register to the WWan factory's "added" signal.

Just add a stub implementation and let it build. More will be added
later.

I'd like to refactor libnm's caching. Note that cached D-Bus objects
have repeated strings all over the place. For example every object will
have a set of D-Bus interfaces (strings) and properties (strings) and an
object path (which is referenced by other objects). We can save a lot of
redundant strings by deduplicating/interning them. Also, by interning
them, we can compare them using pointer equality.

Add a NMRefString implementation for this.

Maybe an alternative name would be NMInternedString or NMDedupString, because
this string gets always interned. There is no way to create a NMRefString
that is not interned. Still, NMRefString name sounds better. It is ref-counted
after all.

Notes:

 - glib has GQuark and g_intern_string(). However, such strings cannot
   be unrefered and are leaked indefinitely. It is thus unsuited for
   anything but a fixed set of well-known strings.

 - glib 2.58 adds GRefString, but we cannot use that because we
   currently still use glib 2.40.
   There are some differences:

     - GRefString is just a typedef to char. That means, the glib API
       exposes GRefString like regular character strings.
       NMRefString intentionally does that not. This makes it slightly
       less convenient to pass it to API that expects "const char *".
       But it makes it clear to the reader, that an instance is in fact
       a NMRefString, which means it indicates that the string is
       interned and can be referenced without additional copy.

     - GRefString can be optionally interned. That means you can
       only use pointer equality for comparing values if you know
       that the GRefString was created with g_ref_string_new_intern().
       So, GRefString looks like a "const char *" pointer and even if
       you know it's a GRefString, you might not know whether it is
       interned. NMRefString is always interned, and you can always
       compare it using pointer equality.

  - In the past I already proposed a different implementation for a
    ref-string. That made different choices. For example NMRefString
    then was a typedef to "const char *", it did not support interning
    but deduplication (without a global cache), ref/unref was not
    thread safe (but then there was no global cache so that two threads
    could still use the API independently).

The point is, there are various choices to make. GRefString, the
previous NMRefString implementation and the one here, all have pros and
cons. I think for the purpose where I intend NMRefString (dedup and
efficient comparison), it is a preferable implementation.

Ah, and of course NMRefString is an immutable string, which is a nice
property.

Fixes: 6e5385a4ebba ('wwan/tests: test service-providers.xml parser')

Fixes build:

  In file included from ../src/devices/wwan/nm-service-providers.c:10:
  In file included from ../shared/nm-default.h:279:
  ../libnm-core/nm-core-types.h:14:10: fatal error: 'nm-core-enum-types.h' file not found
  #include "nm-core-enum-types.h"
           ^
  1 error generated.
  make[2]: *** [src/devices/wwan/src_devices_wwan_tests_test_service_providers-nm-service-providers.o] Error 1

Just a handful of unit tests.

This allows up to look up a default APN if the user doesn't pick one.

This adds LGPL and GFDL texts from the GNU web site and updates the GPL
one:

  COPYING: https://www.gnu.org/licenses/old-licenses/gpl-2.0.txt
  COPYING.LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt
  COPYING.GFDL: https://www.gnu.org/licenses/old-licenses/fdl-1.1.txt

The update to the GPL text is purely cosmetic. However, shipping the
exact same file as GNU publishes may help distros that deduplicate the
license texts or hardlink duplicates.