[RFA/RFC Prec] Add Linux AMD64 process record support second version, 0/3

[Hui Zhu]

Hi guys,

After I send the AMD64 support patch, GDB got big change around
gdbarch.  So I update the patch follow it.

AMD64 patches got some error with testsuite of reverse.  But it looks
like not the bug in AMD64 patches.  I will post a special mail for it.

AMD64 have a lot of thing is different with I386.  So prec doesn't in before.
Now, I make some patches to make prec support AMD64.
Please help me review it that give your comment about it.  Thanks a lot.

There are 3 patches:
1. prec_amd64_tdep.txt This is instruction set support of AMD64.
2. prec_syscall_64bits.txt This is 64 bits system call support.
3. prec_amd64_syscall.txt This is AMD64 Linux system call support.

Thanks,
Hui