udev: hwdb - try reading modalias for usb before falling back to the composed one
udevd: respect the log-level set in /etc/udev/udev.conf

A regression introduced when we moved to systemd's logging is that the only
way to adjust the log-level of the udev daemon is via the env var, kernel
commandline or the commandline.

This reintroduces support for specifying this in the configuration file.

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>
udev: when complaining about invalid characters, print them out

systemd-udevd[6260]: invalid key/value pair in file /usr/lib/udev/rules.d/60-ffado.rules on line 46,starting at character 84 ('#')
udev: fix printf(3) type specifier

src/udev/udev-rules.c: In function 'add_rule':
src/udev/udev-rules.c:1078:33: warning: format '%lu' expects argument of type 'long unsigned int', but argument 8 has type 'int' [-Wformat=]
                                 log_error("invalid key/value pair in file %s on line %u,"
                                 ^