This means we can add a trailing «\» to every element, so that they
can be removed without requiring modification of other lines, and can
be easily sorted.
Replace the old usage of $(nil) which could possibly end up with junk
added if such variable is ever defined, in the environment.
Windows doesn't provide <sys/param.h>. Several libbsd sources require it
for MIN(), and these are useful non-system-specific macros anyway.
Signed-off-by: Guillem Jover <guillem@hadrons.org>
