"Hello world!" linked against libselinux parses /proc/mounts and
whatever else on startup, even when the lib is not needed at all.
Not funny! Get rid of that thing where it's not absolutely needed.
envp is not standardized, and may become invalid when environment variables
are modified. Since udev never actually uses it, we can simply remove it.
Should anyone miss it in future, they can use the standardized environ
variable - like udev_rules.c does already.
