Changes recommended by Chris:

InstSelectSimple.cpp:
  Change the checks for proper I/O port address size into an exit() instead
  of an assertion.  Assertions aren't used in Release builds, and handling
  this error should be graceful (not that this counts as graceful, but it's
  more graceful).

  Modified the generation of the IN/OUT instructions to have 0 arguments.
X86InstrInfo.td:
  Added the OpSize attribute to the 16 bit IN and OUT instructions.

llvm-svn: 12786