Fix types-related warnings based on clang diagnostics

Fix types-related warnings based on clang diagnostics

1. Fix some places where unsigned value compared < 0
2. Fix obsolete %Z specifier to more portable %z
3. Some erroneous types substitution
4. nl_msec2str() - 64-bit msec is now properly used,

Only safe changes. I mean int <--> uint32_t and signed/unsigned fixes.
Some functinos require size_t argument instead of int, but changes of
signatures of that functions is terrible thing.

Also, I do not pretend for a full list of fixes.
Just to shut up clang -Wall -Wextra

One more thing. ifindex. I don't change that because changes will
be too big for simple fix.