Don't use 'parent' in util/dofile.pl

Because we're requiring Perl 5.10.0 and the 'parent' didn't appear
before Perl 5.10.1, we need to resort to the older parent module
declaration style, modifying @ISA.

Reviewed-by: Andy Polyakov <appro@openssl.org>

util/TLSProxy/ClientHello.pm

@@ -55,7 +55,8 @@ use strict;
 
 package TLSProxy::ClientHello;
 
-use parent 'TLSProxy::Message';
+use vars '@ISA';
+push @ISA, 'TLSProxy::Message';
 
 sub new
 {