I have committed a mitigation to libthread_xu in master. It will
munmap the red-zone and any cached thread stacks on unload and avoid
the panic.
I'm not entirely sure whether rtld-elf will safely unwind libc bindings
and other weak symbol overrides, though. libc also has some persistent
state related to threading that might get compromised, so I don't know
if this will work 100%.
I still think the correct solution is to not unload libraries not
designed to be unloadable.
-Matt
