Kickstart: Fix bug in dup2 interception
Kickstart: Fix bug in dup2 interception

Calling get_descriptor twice in dup2 could cause the pointer returned by the first call
to be invalidated.

Actually, I probably need to make access to the descriptor table thread-safe anyway

pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus