The default NetBSD package manager is pkgsrc and it installs Perl
along other third party programs under custom and configurable prefix.
The default prefix for binary prebuilt packages is /usr/pkg, and the
Perl executable lands in /usr/pkg/bin/perl.

This change switches "/usr/bin/perl" to "/usr/bin/env perl" as it's
the most portable solution that should work for almost everybody.
Perl's executable is detected automatically.

This change switches -w option passed to the executable with more
modern "use warnings;" approach. There is no functional change to the
default behavior.

While there, drop "require 5" from scripts/namespace.pl (Perl from 1994?).

Signed-off-by: Kamil Rytarowski <n54@gmx.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Minor perlcritic warning:
headerdep.pl: "return" statement with explicit "undef" at line 84, column 2.  See page 199 of PBP.  (Severity: 5)

The rationale according to PBP is that an explicit return of undef
(contrary to most people's expectations) doesn't
always evaluate as false. It has to with the fact that perl return value
depends on context the function is called. If function is used in
list context, the appropriate return value for false is an empty list;
whereas in scalar context the return value for false is undefined.
By just using a "return" both cases are handled.

In the context of a trivial script this doesn't matter. But one script
may be cut-paste into later code (most people like me only know 50%
of perl), that is why perlcritic always complains

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>

-I takes an argument.  Without this change only a 1 is added to
@opt_include which is not helpful.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>