MFC 262952, 262958, 262966, 262979, 262980, 262986, 262987, 262995, 262997,
    263030, 263033, 263034, 263056, 263057,

  Remove all the redundant external declarations of exception vectors and
  runtime setting of the pointers that's scattered around various places.

  Remove all traces of support for ARM chips prior to the arm9 series.

  Make the default exception handler vectors point to where I thought they
  were already pointing: the default handlers (not a panic that says there
  is no default handler).

  Eliminate irq_dispatch.S.  Move the data items it contained into
  arm/intr.c and the functionality it provided into arm/exception.S.

  Move the exception vector table (so-called "page0" data) into exception.S
  and eliminate vectors.S.

  Change the way the asm GET_CURTHREAD_PTR() macro is defined so that code
  using it doesn't have to have an "AST_LOCALS" macro somewhere in the file.

  Arrange for arm fork_trampoline() to return to userland via the standard
  swi_exit code in exception.S instead of having its own inline expansion
  of the DO_AST and PULLFRAME macros.

  Now that the PUSHFRAME and PULLFRAME macros are used only in the swi
  entry/exit code, they don't need to be macros.  Except that didn't work
  and the whole change was reverted.

  Remove some unnecessary indirection and jump right to the handler functions.

  Use panic rather than printf to "handle" an arm26 address exception
  (should never happen on arm32).

  Remove the unreferenced DATA() macro.

  Remove #include <machine/asmacros.h> from files that don't need it.
MFC 263036, 263059: delete advertising clause in licenses, renumber.
MFC 263199, 263207

  Fix error mesasge in dtc.

  Add tmpfs, mbr, and bsdlabel options back to wandboard kernel config.