Qualify ::File to prevent a stacktrace

Author: HD Moore

lib/rex/post/meterpreter/client.rb

@@ -128,7 +128,7 @@ def init_meterpreter(sock,opts={})
 
     # The SSL certificate is being passed down as a file path
     if opts[:ssl_cert]
-      if ! File.exists? opts[:ssl_cert]
+      if ! ::File.exists? opts[:ssl_cert]
         elog("SSL certificate at #{opts[:ssl_cert]} does not exist and will be ignored")
       else
         # Load the certificate the same way that SslTcpServer does it