minor: add use "warnings"; to every perl script

tools/test_modules/m05500.pm

@@ -6,6 +6,7 @@
 ##
 
 use strict;
+use warnings;
 
 use Authen::Passphrase::NTHash;
 use Digest::HMAC qw (hmac hmac_hex);

tools/test_modules/m05600.pm

@@ -6,6 +6,7 @@
 ##
 
 use strict;
+use warnings;
 
 use Authen::Passphrase::NTHash;
 use Digest::HMAC qw (hmac hmac_hex);

tools/test_modules/m05700.pm

@@ -6,6 +6,7 @@
 ##
 
 use strict;
+use warnings;
 
 use Digest::SHA  qw (sha256);
 use MIME::Base64 qw (encode_base64);

tools/test_modules/m05800.pm

@@ -6,6 +6,7 @@
 ##
 
 use strict;
+use warnings;
 
 use Digest::SHA  qw (sha1);