Add more _printf_'s for format-nonliterals

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.