Imported a copy of libudis86 1.7.1

A robust disassembler capable of disassembling most (all?) of the
32bit & 64bit Intel assembler instructions. The plan is to use this
instead of our home-grown (and incomplete) disassembler.
Use libudis86 for disassembling instructions for x86 and x64

This makes hooking the 'Tcl_EvalObjEx' function in the Tcl library on OS
X work. It probably fixes quite a few other cases in which a "some
instructions unknown!" messages was printed as well. As a nice side
effect, it allows throwing away the custom code for recognizing and
skipping instructions.

All tests still pass.