x86: implement fild, fucomi, and fucomip x87 insts

fild loads an integer value into the x87 top of stack register.
fucomi/fucomip compare two x87 register values (the latter
also doing a stack pop).
These instructions are used by some versions of GNU libstdc++.

x86: implements x87 mult/div instructions

x86: implements x87 add/sub instructions

x86: implements fxch instruction.

x86: Add support for FLDENV & FNSTENV

x86: Add support for loading 32-bit and 80-bit floats in the x87

The x87 FPU supports three floating point formats: 32-bit, 64-bit, and
80-bit floats. The current gem5 implementation supports 32-bit and
64-bit floats, but only works correctly for 64-bit floats. This
changeset fixes the 32-bit float handling by correctly loading and
rounding (using truncation) 32-bit floats instead of simply truncating
the bit pattern.

80-bit floats are loaded by first loading the 80-bits of the float to
two temporary integer registers. A micro-op (cvtint_fp80) then
converts the contents of the two integer registers to the internal FP
representation (double). Similarly, when storing an 80-bit float,
there are two conversion routines (ctvfp80h_int and cvtfp80l_int) that
convert an internal FP register to 80-bit and stores the upper 64-bits
or lower 32-bits to an integer register, which is the written to
memory using normal integer stores.

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

x86: implements fsin, fcos instructions

x86: implement fabs, fchs instructions

x86: implement x87 fp instruction fnstsw
This patch implements the fnstsw instruction. The code was originally written
by Vince Weaver. Gabe had made some comments about the code, but those were
never addressed. This patch addresses those comments.

x86: implement x87 fp instruction fsincos
This patch implements the fsincos instruction. The code was originally written
by Vince Weaver. Gabe had made some comments about the code, but those were
never addressed. This patch addresses those comments.

X86: Decode the mysterious and elusive ffreep x87 instruction.

The internet says this instruction was created by accident when an Intel CPU
failed to decode x87 instructions properly. It's been documented on a few rare
occasions and has generally worked to ensure backwards compatability. One
source claims that the gcc toolchain is basically the only thing that emits
it, and that emulators/binary translators like qemu and bochs implement it.

We won't actually implement it here since we're hardly implementing any other
x87 instructions either. If we were to implement it, it would behave the same
as ffree but then also pop the register stack.

http://www.pagetable.com/?p=16

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

X86: Fix the decoding for and fill out FST and FSTP.

X86: Make "Inst" the default format instead of WarnUnimpl for one byte opcodes.

X86: Implement the fld, fst, and fstp instructions.

X86: Add operand type information to the fnstcw and fldw instruction placeholders.
These are the only floating point instructions that get used in my simple hello world test. These instructions are for setting up the floating point control register. Their not being implemented doesn't affect anything because floating point isn't used.

X86: Add decoding for x87 floating point.