llvm-ar: Fix MinGW compilation

llvm-ar is using CompareStringOrdinal which is available
only starting with Windows Vista (WINVER 0x600).

Fix this by hoising WindowsSupport.h, which sets _WIN32_WINNT
to 0x0601, up to llvm/include/llvm/Support and use it in llvm-ar.

Patch by Cristian Adam!

Differential revision: https://reviews.llvm.org/D74599

lib/Support/CrashRecoveryContext.cpp

@@ -254,7 +254,7 @@ bool CrashRecoveryContext::RunSafely(function_ref<void()> Fn) {
 // XP, so if support for older versions of Windows is required,
 // it will have to be added.
 
-#include "Windows/WindowsSupport.h"
+#include "llvm/Support/Windows/WindowsSupport.h"
 
 static LONG CALLBACK ExceptionHandler(PEXCEPTION_POINTERS ExceptionInfo)
 {

lib/Support/InitLLVM.cpp

@@ -15,7 +15,7 @@
 #include <string>
 
 #ifdef _WIN32
-#include "Windows/WindowsSupport.h"
+#include "llvm/Support/Windows/WindowsSupport.h"
 #endif
 
 using namespace llvm;

lib/Support/RandomNumberGenerator.cpp

@@ -17,7 +17,7 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 #ifdef _WIN32
-#include "Windows/WindowsSupport.h"
+#include "llvm/Support/Windows/WindowsSupport.h"
 #else
 #include "Unix/Unix.h"
 #endif

lib/Support/Windows/DynamicLibrary.inc

@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "WindowsSupport.h"
+#include "llvm/Support/Windows/WindowsSupport.h"
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/raw_ostream.h"
 

lib/Support/Windows/Host.inc

@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "WindowsSupport.h"
+#include "llvm/Support/Windows/WindowsSupport.h"
 #include <cstdio>
 #include <string>
 

lib/Support/Windows/Memory.inc

@@ -17,7 +17,7 @@
 #include "llvm/Support/WindowsError.h"
 
 // The Windows.h header must be the last one included.
-#include "WindowsSupport.h"
+#include "llvm/Support/Windows/WindowsSupport.h"
 
 static DWORD getWindowsProtectionFlags(unsigned Flags) {
   switch (Flags & llvm::sys::Memory::MF_RWE_MASK) {

lib/Support/Windows/Path.inc

@@ -25,7 +25,7 @@
 
 // These two headers must be included last, and make sure shlobj is required
 // after Windows.h to make sure it picks up our definition of _WIN32_WINNT
-#include "WindowsSupport.h"
+#include "llvm/Support/Windows/WindowsSupport.h"
 #include <shellapi.h>
 #include <shlobj.h>
 

lib/Support/Windows/Process.inc

@@ -19,7 +19,7 @@
 #include <malloc.h>
 
 // The Windows.h header must be after LLVM and standard headers.
-#include "WindowsSupport.h"
+#include "llvm/Support/Windows/WindowsSupport.h"
 
 #include <direct.h>
 #include <io.h>

lib/Support/Windows/Program.inc

@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "WindowsSupport.h"
+#include "llvm/Support/Windows/WindowsSupport.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/Errc.h"

lib/Support/Windows/Signals.inc

@@ -23,7 +23,7 @@
 #include "llvm/Support/raw_ostream.h"
 
 // The Windows.h header must be after LLVM and standard headers.
-#include "WindowsSupport.h"
+#include "llvm/Support/Windows/WindowsSupport.h"
 
 #ifdef __MINGW32__
  #include <imagehlp.h>

lib/Support/Windows/ThreadLocal.inc

@@ -15,7 +15,7 @@
 //===          is guaranteed to work on *all* Win32 variants.
 //===----------------------------------------------------------------------===//
 
-#include "WindowsSupport.h"
+#include "llvm/Support/Windows/WindowsSupport.h"
 #include "llvm/Support/ThreadLocal.h"
 
 namespace llvm {

lib/Support/Windows/Threading.inc

@@ -13,7 +13,7 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/Twine.h"
 
-#include "WindowsSupport.h"
+#include "llvm/Support/Windows/WindowsSupport.h"
 #include <process.h>
 
 #include <bitset>

lib/Support/raw_ostream.cpp

@@ -60,7 +60,7 @@
 
 #ifdef _WIN32
 #include "llvm/Support/ConvertUTF.h"
-#include "Windows/WindowsSupport.h"
+#include "llvm/Support/Windows/WindowsSupport.h"
 #endif
 
 using namespace llvm;

tools/llvm-ar/llvm-ar.cpp

@@ -46,8 +46,7 @@
 #endif
 
 #ifdef _WIN32
-#define WIN32_LEAN_AND_MEAN
-#include <windows.h>
+#include "llvm/Support/Windows/WindowsSupport.h"
 #endif
 
 using namespace llvm;