build_rtnl_addr() has two parameters "lifetime" and "preferred". Both
count from *now*.
Fix nmp_object_to_nl() to properly set these timestamps. This bug had
not real consequences, because the only place where we use
nmp_object_to_nl() the arguments are 0.
There is no general purpose file for platform utilities.
We only have nm-platform.h, which contains (mostly) functions
that operate on a NMPlatform instance (and that can be mocked
using NMFakePlatform).
Add a new file for independent utility functions. nm-platform-utils.c
should not call into functions having a NMPlatform instance, to
have them independent from platform caching and the platform
singleton.