MFC 232744,232747,233031:

MFC 232744,232747,233031:
- Allow a native i386 kernel to be built with 'nodevice atpic'.  Just as on
  amd64, if 'device isa' is present quiesce the 8259A's during boot and
  resume from suspend.
- Move i386's intr_machdep.c to the x86 tree and share it with amd64.
- Merge r232744 changes to pc98.
  (Allow a kernel to be built with 'nodevice atpic'.)
- Move ICU related defines from x86/isa/atpic.c to x86/isa/icu.h and
  use them in x86/x86/intr_machdep.c.

Note, I normally would have merged 232747 separately, but 233031 assumed
232747 was already merged and 232744 needs to be merged with 233031.

git-svn-id: svn://svn.freebsd.org/base/stable/9@234144 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f