perl: Don't hardcode interpreter path

This is particularly useful on operating systems that don't ship
Perl as part of the base system (eg. FreeBSD) while still working
just as well as it did before on Linux.

In one case (src/rpc/genprotocol.pl) the interpreter path was
missing altogether.
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>

build-aux/augeas-gentest.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # augeas-gentest.pl: Generate an augeas test file, from an
 #                    example config file + test file template

build-aux/check-spacing.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # check-spacing.pl: Report any usage of 'function (..args..)'
 # Also check for other syntax issues, such as correct use of ';'

build-aux/mock-noinline.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 my %noninlined;
 my %mocked;

build-aux/prohibit-duplicate-header.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 use strict;
 

docs/genaclperms.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # Copyright (C) 2013 Red Hat, Inc.
 #

docs/hvsupport.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 use strict;
 use warnings;

src/access/genpolkit.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # Copyright (C) 2012-2013 Red Hat, Inc.
 #

src/check-aclperms.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # Copyright (C) 2013 Red Hat, Inc.
 #

src/check-aclrules.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # Copyright (C) 2013-2014 Red Hat, Inc.
 #

src/check-driverimpls.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # Copyright (C) 2013 Red Hat, Inc.
 #

src/check-drivername.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # Copyright (C) 2013 Red Hat, Inc.
 #

src/check-symfile.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 # Copyright (C) 2012-2013 Red Hat, Inc.
 #

src/check-symsorting.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 # Copyright (C) 2012-2013 Red Hat, Inc.
 #

src/dtrace2systemtap.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # Copyright (C) 2011-2012 Red Hat, Inc.
 #

src/rpc/gendispatch.pl

-#!/usr/bin/perl -w
+#!/usr/bin/env perl
 #
 # Copyright (C) 2010-2015 Red Hat, Inc.
 #
@@ -32,6 +32,7 @@
 # Extended by Matthias Bolte <matthias.bolte@googlemail.com>
 
 use strict;
+use warnings;
 
 use Getopt::Long;
 

src/rpc/genprotocol.pl

+#!/usr/bin/env perl
 #
 # Generate code for an XDR protocol, optionally applying
 # fixups to the glibc rpcgen code so that it compiles

src/rpc/gensystemtap.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # Copyright (C) 2011-2012 Red Hat, Inc.
 #

tests/check-file-access.pl

-#!/usr/bin/perl -w
+#!/usr/bin/env perl
 #
 # Copyright (C) 2016 Red Hat, Inc.
 #

tests/oomtrace.pl

-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 use strict;
 use warnings;