[lldb][AIX] HostInfoAIX Support (#117906)

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

Added a HostInfoAIX file for the AIX platform. 
Most of the common functionalities are handled by the parent
HostInfoPosix now,
So we just have some basic functions implemented here.

lldb/include/lldb/Host/aix/HostInfoAIX.h

@@ -0,0 +1,28 @@
+//===-- HostInfoAIX.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_HOST_AIX_HOSTINFOAIX_H_
+#define LLDB_HOST_AIX_HOSTINFOAIX_H_
+
+#include "lldb/Host/posix/HostInfoPosix.h"
+#include "lldb/Utility/FileSpec.h"
+
+namespace lldb_private {
+
+class HostInfoAIX : public HostInfoPosix {
+  friend class HostInfoBase;
+
+public:
+  static void Initialize(SharedLibraryDirectoryHelper *helper = nullptr);
+  static void Terminate();
+
+  static FileSpec GetProgramFileSpec();
+};
+} // namespace lldb_private
+
+#endif // LLDB_HOST_AIX_HOSTINFOAIX_H_

lldb/source/Host/CMakeLists.txt

@@ -133,6 +133,11 @@ else()
       openbsd/Host.cpp
       openbsd/HostInfoOpenBSD.cpp
       )
+
+  elseif (CMAKE_SYSTEM_NAME MATCHES "AIX")
+    add_host_subdirectory(aix
+      aix/HostInfoAIX.cpp
+      )    
   endif()
 endif()
 

lldb/source/Host/aix/HostInfoAIX.cpp

@@ -0,0 +1,22 @@
+//===-- HostInfoAIX.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 "lldb/Host/aix/HostInfoAIX.h"
+
+using namespace lldb_private;
+
+void HostInfoAIX::Initialize(SharedLibraryDirectoryHelper *helper) {
+  HostInfoPosix::Initialize(helper);
+}
+
+void HostInfoAIX::Terminate() { HostInfoBase::Terminate(); }
+
+FileSpec HostInfoAIX::GetProgramFileSpec() {
+  static FileSpec g_program_filespec;
+  return g_program_filespec;
+}