Copy new process argument list in do_execve() before grabbing PROC_LOCK to avoid touching pageable memory while holding a mutex.
Copy new process argument list in do_execve() before grabbing PROC_LOCK
to avoid touching pageable memory while holding a mutex.

Simplify argument list replacement logic.

PR:		kern/84935
Submitted by:	"Antoine Pelisse" apelisse AT gmail.com (in a different form)
MFC after:	3 days

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