[lldb] [Process/NetBSD] Remove unused orig_*ax use

[mgorny]

Summary

orig_*ax logic is Linux-specific, and was never used on NetBSD.
In fact, its support seems to be a dead code entirely.

[labath]

This seems fine, though it may be worth checking what happens when running expressions while the process is stopped in a syscall (does the expression run correctly, does the syscall resume correctly, etc.)...

lldb/source/Plugins/Process/NetBSD/NativeRegisterContextNetBSD_x86_64.cpp

Status NativeRegisterContextNetBSD_x86_64::ReadAllRegisterValues(
   error = ReadRegisterSet(GPRegSet);
   if (error.Fail())
     return error;
 
   uint8_t *dst = data_sp->GetBytes();
   ::memcpy(dst, &m_gpr_x86_64, GetRegisterInfoInterface().GetGPRSize());
   dst += GetRegisterInfoInterface().GetGPRSize();
 
-  RegisterValue value((uint64_t)-1);
-  const RegisterInfo *reg_info =
-      GetRegisterInfoInterface().GetDynamicRegisterInfo("orig_eax");
-  if (reg_info == nullptr)
-    reg_info = GetRegisterInfoInterface().GetDynamicRegisterInfo("orig_rax");
   return error;
 }
 
 Status NativeRegisterContextNetBSD_x86_64::WriteAllRegisterValues(
     const lldb::DataBufferSP &data_sp) {
   Status error;
 
   if (!data_sp) {