[Windows, Process] LLDB reads wrong registers on 64bit Windows

Summary: LLDB reads wrong registers on 64bit Windows because RegisterContextWindows_x64::GetRegisterInfoAtIndex returns wrong reference.
I encountered broken backtrace when the program stopped at function which does not have prologue code, such as compiled with '-fomit-frame-pointer'.
In this situation, CFA is equal to rsp but LLDB reads r9.

RegisterContextWindows_x64::GetRegisterInfoAtIndex depends the order of lldb_XXX_x86_64 values, but RegisterIndex/g_register_infos/g_gpr_reg_indices does not follow order.

In source/Plugins/Process/Utility/lldb-x86-register-enums.h
The order of GPRs is rax, rbx, rcx, rdx, rdi, rsi, rbp, rsp, r8, ...

In source/Plugins/Process/Windows/Common/x64/RegisterContextWindows_x64.cpp
The order of GPRs is rax, rbx, rcx, rdx, rdi, rsi, r8, r9, r10, ...

Patch by Kenji Koyanagi

llvm-svn: 332671