[lldb][AIX] Adding NativeThreadAIX (#139537)

This PR is in reference to porting LLDB on AIX.

Link to discussions on llvm discourse and github:

1. https://discourse.llvm.org/t/port-lldb-to-ibm-aix/80640
2. #101657
The complete changes for porting are present in this draft PR:
#102601

**Description:**
Adding NativeThreadAIX base files, 
to be integrated with already merged NativeProcessAIX.

Author: DhruvSrivastavaX

lldb/source/Plugins/Process/AIX/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_lldb_library(lldbPluginProcessAIX
   NativeProcessAIX.cpp
+  NativeThreadAIX.cpp
 
   LINK_LIBS
     lldbCore

lldb/source/Plugins/Process/AIX/NativeThreadAIX.cpp

@@ -0,0 +1,58 @@
+//===-- NativeThreadAIX.cpp ---------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "NativeThreadAIX.h"
+#include "NativeProcessAIX.h"
+#include "lldb/Utility/State.h"
+
+using namespace lldb;
+using namespace lldb_private;
+using namespace lldb_private::process_aix;
+
+NativeThreadAIX::NativeThreadAIX(NativeProcessAIX &process, lldb::tid_t tid)
+    : NativeThreadProtocol(process, tid), m_state(StateType::eStateInvalid) {}
+
+std::string NativeThreadAIX::GetName() { return ""; }
+
+lldb::StateType NativeThreadAIX::GetState() { return m_state; }
+
+bool NativeThreadAIX::GetStopReason(ThreadStopInfo &stop_info,
+                                    std::string &description) {
+  return false;
+}
+
+Status NativeThreadAIX::SetWatchpoint(lldb::addr_t addr, size_t size,
+                                      uint32_t watch_flags, bool hardware) {
+  return Status("Unable to Set hardware watchpoint.");
+}
+
+Status NativeThreadAIX::RemoveWatchpoint(lldb::addr_t addr) {
+  return Status("Clearing hardware watchpoint failed.");
+}
+
+Status NativeThreadAIX::SetHardwareBreakpoint(lldb::addr_t addr, size_t size) {
+  return Status("Unable to set hardware breakpoint.");
+}
+
+Status NativeThreadAIX::RemoveHardwareBreakpoint(lldb::addr_t addr) {
+  return Status("Clearing hardware breakpoint failed.");
+}
+
+NativeProcessAIX &NativeThreadAIX::GetProcess() {
+  return static_cast<NativeProcessAIX &>(m_process);
+}
+
+const NativeProcessAIX &NativeThreadAIX::GetProcess() const {
+  return static_cast<const NativeProcessAIX &>(m_process);
+}
+
+llvm::Expected<std::unique_ptr<llvm::MemoryBuffer>>
+NativeThreadAIX::GetSiginfo() const {
+  return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                 "Not implemented");
+}

lldb/source/Plugins/Process/AIX/NativeThreadAIX.h

@@ -0,0 +1,53 @@
+//===-- NativeThreadAIX.h ----------------------------------- -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLDB_SOURCE_PLUGINS_PROCESS_AIX_NATIVETHREADAIX_H_
+#define LLDB_SOURCE_PLUGINS_PROCESS_AIX_NATIVETHREADAIX_H_
+
+#include "lldb/Host/common/NativeThreadProtocol.h"
+
+namespace lldb_private::process_aix {
+
+class NativeProcessAIX;
+
+class NativeThreadAIX : public NativeThreadProtocol {
+  friend class NativeProcessAIX;
+
+public:
+  NativeThreadAIX(NativeProcessAIX &process, lldb::tid_t tid);
+
+  // NativeThreadProtocol Interface
+  std::string GetName() override;
+
+  lldb::StateType GetState() override;
+
+  bool GetStopReason(ThreadStopInfo &stop_info,
+                     std::string &description) override;
+
+  Status SetWatchpoint(lldb::addr_t addr, size_t size, uint32_t watch_flags,
+                       bool hardware) override;
+
+  Status RemoveWatchpoint(lldb::addr_t addr) override;
+
+  Status SetHardwareBreakpoint(lldb::addr_t addr, size_t size) override;
+
+  Status RemoveHardwareBreakpoint(lldb::addr_t addr) override;
+
+  NativeProcessAIX &GetProcess();
+
+  const NativeProcessAIX &GetProcess() const;
+
+  llvm::Expected<std::unique_ptr<llvm::MemoryBuffer>>
+  GetSiginfo() const override;
+
+private:
+  lldb::StateType m_state;
+};
+} // namespace lldb_private::process_aix
+
+#endif // #ifndef LLDB_SOURCE_PLUGINS_PROCESS_AIX_NATIVETHREADAIX_H_