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.
As we do not have cooperation from the crt0 code to set __progname, we
have to set it ourselves from getprogname() in case it's NULL. On GNU
systems we can use program_invocation_short_name which is actually set
on crt0.
This is more correct as the strings are not going to be changed, and it
matches the function signatures on other BSDs.
Suggested-by: Aurelien Jarno <aurel32@debian.org>
