These are required due to the O_* macro usage, but have passed
undetected on glibc-based systems due to implicit inclusions.
Signed-off-by: Guillem Jover <guillem@hadrons.org>
This means that software being ported should not need to be modified in
the usual case, as the libbsd headers will take over the standard
namespace and fill the missing gaps, and include the system headers.
To use this the new libbsd-transparent.pc file can be used through
pkg-config, which should end up doing the right thing.
