MFC 238109,238166:

MFC 238109,238166:
Several fixes to the amd64 disassembler:
- Decode the 'xsave', 'xrstor', 'xsaveopt', 'xgetbv', 'xsetbv', and
  'rdtscp' instructions.
- Add generic support for opcodes that are escape bytes used for
  multi-byte opcodes (such as the 0x0f prefix).  Use this to replace
  the hard-coded 0x0f special case and add support for three-byte
  opcodes that use the 0x0f38 prefix.
- Decode all Intel VMX instructions.  invept and invvpid in particular are
  three-byte opcodes that use the 0x0f38 escape prefix.
- Rework how the special 'SDEP' size flag works such that the default
  instruction name (i_name) is the instruction when the data size
  prefix (0x66) is not specified, and the alternate name in i_extra is
  used when the prefix is included.
- Add a new 'ADEP' size flag similar to 'SDEP' except that it chooses
  between i_name and i_extra based on the address size prefix (0x67).
  Use this to fix the decoding for jrcxz vs jecxz which is determined
  by the address size prefix, not the operand size prefix.  Also, jcxz
  is not possible in 64-bit mode, but jrcxz is the default instruction
  for that opcode.
- Add support for handling instructions that have a mandatory 'rep'
  prefix (this means not outputting the 'repe ' prefix until determining
  if it is used as part of an opcode).  Make 'pause' less of a special
  case this way.
- Decode 'cmpxchg16b' and 'cdqe' which are variants of other instructions
  but with a REX.W prefix.

git-svn-id: svn://svn.freebsd.org/base/stable/9@239879 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f