Remove unused dbus_get_pid_from_bus_name()

If something like this is needed later on, it must be re-implemented
without using dbus_send_with_block().
Allow users of dbus_send_ex() to get pending call handle

This is needed if the pending call needs to be cancelled.
Rewrite mce-sensorfw module so that it does not use blocking dbus calls

The semi procedural logic is replaced by stacked state machines
that should ensure that mce is never blocked if sensord gets stuck
for some reason.

Externally the interface provided by mce-sensorfw does not change.

[mce] Rewrite mce-sensorfw module so that it does not use blocking dbus calls. Fixes JB#17747
Change indentation style of mce-sensorfw.h
Do not list mce-sensorfw.c twice in the Makefile

Remove duplicate entry.
Drop sysinfod support

The sysinfod service is provided by proprietary Nokia component
and the compatibility has already been disabled for almost two
years.

Since get_sysinfo_value() was the last place within mce itself
to use blocking dbus method calls, dropping support altogether
allows removal of blocking dbus call helpers too.
Remove unused dbus_send_with_block() function

Future MCE code should never use blocking dbus ipc and thus the
helper for making them is removed.
Add state transition diagram for mce-sensorfw module

Can be turned in to a png file with dot from graphviz package:
  dot -Tpng mce-sensorfw.dot -o mce-sensorfw.png
Fix pending call unref convention for dbus_send() helper functions

Legacy way of dealing with asynchronous dbus method calls in mce was to
a) leave one extra ref to pending call when issuing the method call
b) call dbus_pending_call_unref() from handler callback
Which is problematic since (b) does not happen if the pending call is
canceled.

Now the extra reference is cleared after it is no longer needed and
calls to dbus_pending_call_unref() from all related handler callbacks
are removed.
Remove unused debug logging

These were accidentally left in after testing.
Fix whitespace
Remove dead code

Leftovers from testing and evolving logic.
Check logging verbosity before evaluating format parameters

Vast majority of diagnostic logging from mce is not emitted to journal
on default verbosity. Spending cpu time evaluating format parameters
and pushing them to stack just to be discarded makes no sense.

Now verbosity level is checked 1st and potentially time consuming
parameter evaluation is done only if the message is going to be
emitted to the journal.

[mce] Check logging verbosity before evaluating format parameters. Fixes JB#22310
Fix various issues in mce-log.h

Reserved symbol names (__xxx, _XXX_, etc) were replaced with XXX_.

Added missing dummy counterparts for real functions and removed
useless and repetitive doxygen documentation of all dummies.

Indented #if blocks to make nesting level more visible.

Split long lines.
Remove external pending call reference when reply message is received

Used to just clear the pointer, which created a memory leak.
Unify whitespace
Remove evdev I/O watches on mce exit

Makes valgrind output less noisy.
Release setting change signal cache on mce exit

Makes valgrind output less noisy.
Remove main D-Bus signal filter on mce exit

Makes valgrind output less noisy.
Cleanup signal transfer pipe on mce exit

Makes valgrind output less noisy.