WIP Integrate Capstone/Keystone

[Isaac0616]

I am surveying the possibility of integrating Capstone/Keystone as mentioned in #683. This is a pretty early and untested draft, but I want to bring up some discussion.

Here are some of my implementation choices.

1. Currently, if I install Keystone by pip on Ubuntu, it can not correctly find the libkeystone.so. I have to compile it manually. Do we want to do this in setup.py for users?
2. I move original asm/disasm to _asm_binutil/_disasm_binutil as a fallback because binutil support some architectures (e.g., ia64) which Capstone/Keystone don't support.
3. Still rely on external cpp to support SYS_xxx.
4. It seems that Capstone/Keystone do not support "real" 32-bit mode for some architectures. For example,

>>> ks = Ks(KS_ARCH_SPARC, KS_MODE_SPARC32)
>>> ks.asm("srlx %r1, %r2, %r3", as_bytes=True)
('\x02P0\x87', 1L)

>>> ks = Ks(KS_ARCH_PPC, KS_MODE_PPC32+KS_MODE_BIG_ENDIAN)
>>> ks.asm('rldicr  4,4,32,31', as_bytes=True)
('x\x84\x07\xc6', 1L)

Unlike binutil, 32-bit Sparc and PowerPC will not throw any exception when assembling 64-bit instructions. Capstone doesn't have corresponding 32-bit mode for Sparc and PowerPC. Should we fallback to binutil for them?
5. For implementation simplicity, disasm would show

   0:   b85d000000              mov    eax, 0x5d

instead of

   0:   b8 5d 00 00 00          mov    eax,0x5d

Besides, the spacing is also slightly different.

Any suggestions on these points?

[heapcrash]

Closing this out since the PR is two+ years old. Please rebase your changes on top of the current dev branch or create a new PR to get this merged.