Perl Safe.pm compartment reuse vuln

[Rain Forest Puppy <rfp () vulnwatch org>]

A bug was found in Perl's Safe.pm module:

http://use.perl.org/articles/02/10/06/1118222.shtml?tid=5

Basically, code in the sandbox can modify the execution/operation mask via
@_; if the compartment was ever reused, the second time around it might
use the modified execution mask.

Perl <= 5.8.0 are vuln.

- rfp