Fix mlnx.pl script for perl include local directory (sonic-net#540)

For new Perl @inc path must be updated for current directory module
lookup

Author: kcudnik

tests/mlnx.pl

@@ -1,5 +1,7 @@
 #!/usr/bin/perl
 
+BEGIN { push @INC,'.'; }
+
 use strict;
 use warnings;
 use diagnostics;