Restored FAKE_MCOUNT() and MEXITCOUNT invocations and adjusted them for amd64 as necessary.  This is routine, except: - the FAKE_MCOUNT($bintr) in doreti was missing the '$'.  This gave a   a garbage address made up of padding bytes (with the nop byte 0x90 as   the MSB) instead of the intended address of bintr.  This accidentally   worked on i386's because (0x90 << 24) is close enough to bintr, but   it doesn't work on amd64's because (0x90 << 56) is much further away   from bintr. - the FAKE_MCOUNT($btrap) in calltrap was similarly broken.  It hasn't   been needed since FreeBSD-1, so just delete it.
Restored FAKE_MCOUNT() and MEXITCOUNT invocations and adjusted them for
amd64 as necessary.  This is routine, except:
- the FAKE_MCOUNT($bintr) in doreti was missing the '$'.  This gave a
  a garbage address made up of padding bytes (with the nop byte 0x90 as
  the MSB) instead of the intended address of bintr.  This accidentally
  worked on i386's because (0x90 << 24) is close enough to bintr, but
  it doesn't work on amd64's because (0x90 << 56) is much further away
  from bintr.
- the FAKE_MCOUNT($btrap) in calltrap was similarly broken.  It hasn't
  been needed since FreeBSD-1, so just delete it.

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase