Instead of waiting for new data from the sensor, which might be
a long time coming, depending on the sensor device, ask the kernel
for the last state for that particular input device.
Clang is a bit more strict wrt format-nonliterals:
http://clang.llvm.org/docs/LanguageExtensions.html#format-string-checking
Adding these extra printf attributes also makes gcc able to find more
problems. E.g. this patch uncovers a format issue in udev-builtin-path_id.c
Some parts looked intetional about breaking the format-nonliteral check.
I added some supression for warnings there.
As we were searching by ID_PATH, it would have been possible
for us to find a sibling device instead of the device we were
looking for.
This fixes device matching on the WeTab with the upstream kernel,
as it was trying to use the "Asus Laptop extra buttons" device
instead of the accelerometer.
