[win] Consolidate windows.h include tips and tricks

src/hb-atomic-private.hh

@@ -44,10 +44,6 @@
 
 #elif !defined(HB_NO_MT) && (defined(_WIN32) || defined(__CYGWIN__))
 
-#define WIN32_LEAN_AND_MEAN
-#ifndef _WIN32_WINNT
-#define _WIN32_WINNT 0x0600
-#endif
 #include <windows.h>
 
 /* MinGW has a convoluted history of supporting MemoryBarrier

src/hb-mutex-private.hh

@@ -44,7 +44,6 @@
 
 #elif !defined(HB_NO_MT) && (defined(_WIN32) || defined(__CYGWIN__))
 
-#define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 typedef CRITICAL_SECTION hb_mutex_impl_t;
 #define HB_MUTEX_IMPL_INIT	{ NULL, 0, 0, NULL, NULL, 0 }

src/hb-private.hh

@@ -116,6 +116,18 @@
 #define HB_FUNC __func__
 #endif
 
+#ifdef _WIN32
+   /* We need Windows Vista for both Uniscribe backend and for
+    * MemoryBarrier.  We don't support compiling on Windows XP,
+    * though we run on it fine. */
+#  if defined(_WIN32_WINNT) && _WIN32_WINNT < 0x0600
+#    undef _WIN32_WINNT
+#  endif
+#  ifndef _WIN32_WINNT
+#    define _WIN32_WINNT 0x0600
+#  endif
+#  define WIN32_LEAN_AND_MEAN
+#endif
 
 
 /* Basics */

src/hb-uniscribe.cc

@@ -24,9 +24,6 @@
  * Google Author(s): Behdad Esfahbod
  */
 
-#define _WIN32_WINNT 0x0600
-#define WIN32_LEAN_AND_MEAN
-
 #define HB_SHAPER uniscribe
 #include "hb-shaper-impl-private.hh"
 

src/hb-uniscribe.h

@@ -29,9 +29,6 @@
 
 #include "hb.h"
 
-#ifndef _WIN32_WINNT
-#define _WIN32_WINNT 0x0600
-#endif
 #include <windows.h>
 
 HB_BEGIN_DECLS