nat; Start to use gcc attribute to say that parameter may not be zero

This is an attempt to hint the compiler that it should check
the parameters and warn when something is null. Sadly it does
not work as expected.
1 file changed
tree: bcf8cc656c671d558389063fcb506e5e622ad636
  1. hlrsync/
  2. linux-kernel/
  3. openbsc/
  4. wireshark/