[lldb][AIX] GetOpt support in AIX (llvm#120574)

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. llvm#101657
The complete changes for porting are present in this draft PR:
llvm#102601

Adding changes for minimal build for lldb binary on AIX. 
getopt.h is missing in AIX, so instead relying on LLDB's getopt
functions.

Author: DhruvSrivastavaX

lldb/include/lldb/Host/HostGetOpt.h

@@ -9,7 +9,7 @@
 #ifndef LLDB_HOST_HOSTGETOPT_H
 #define LLDB_HOST_HOSTGETOPT_H
 
-#if !defined(_MSC_VER) && !defined(__NetBSD__)
+#if !defined(_MSC_VER) && !defined(__NetBSD__) && !defined(_AIX)
 
 #include <getopt.h>
 #include <unistd.h>

lldb/include/lldb/Host/common/GetOptInc.h

@@ -11,11 +11,11 @@
 
 #include "lldb/lldb-defines.h"
 
-#if defined(_MSC_VER)
+#if defined(_MSC_VER) || defined(_AIX)
 #define REPLACE_GETOPT
 #define REPLACE_GETOPT_LONG
 #endif
-#if defined(_MSC_VER) || defined(__NetBSD__)
+#if defined(_MSC_VER) || defined(__NetBSD__) || defined(_AIX)
 #define REPLACE_GETOPT_LONG_ONLY
 #endif