Migrate ie->ie_assign_cpu and associated code to use an int for CPU rather
than u_char.

Migrate post_filter to use an int for a CPU rather than u_char.

Change intr_event_bind() to use an int for CPU rather than u_char.

It touches the ppc, sparc64, arm and mips machdep code but it should
(hah!) be a no-op.

Tested:

* i386, AMD64 laptops

Reviewed by:	jhb


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271712 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f