x86: Fix loading of floating point constants

This changeset actually fixes two issues:

* The lfpimm instruction didn't work correctly when applied to a
floating point constant (it did work for integers containing the
bit string representation of a constant) since it used
reinterpret_cast to convert a double to a uint64_t. This caused a
compilation error, at least, in gcc 4.6.3.

* The instructions loading floating point constants in the x87
processor didn't work correctly since they just stored a truncated
integer instead of a double in the floating point register. This
changeset fixes the old microcode by using lfpimm instruction
instead of the limm instructions.

x86: implement some of the x87 instructions
This patch implements ftan, fprem, fyl2x, fld* floating-point instructions.

copyright: Change HP copyright on x86 code to be more friendly

X86: Put in stubs for x87, 64 bit and 128 bit SIMD instruction microcode.