kernel/poll: Remove dummy waitq from stack
kernel/poll: Remove dummy waitq from stack

The poll code uses a dummy wait queue so the threads have something to
block on, but the previous coherence pass (which rearranged things to
put the _poller data elsewhere) missed that this was on the stack,
which is not allowed.  It actually has no use except as a list, so
make it a global static instead.

Signed-off-by: Andy Ross <c70f9a6bf6ee0cd69c8af4ce5e6b131945769315@intel.com>

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