MSVC 9.0 (VS2008) does not support Windows build targets prior to WinXP,

and makes wrong asumptions of build target when it isn't specified. So,
if no build target has been defined we will target WinXP when building
with MSVC 9.0 (VS2008).

config-win32.h

@@ -169,6 +169,20 @@
 #define _CRT_NONSTDC_NO_DEPRECATE 1
 #endif
 
+/* VS2008 does not support Windows build targets prior to WinXP, */
+/* so, if no build target has been defined we will target WinXP. */
+#if defined(_MSC_VER) && (_MSC_VER >= 1500)
+#  ifndef _WIN32_WINNT
+#    define _WIN32_WINNT 0x0501
+#  endif
+#  ifndef WINVER
+#    define WINVER 0x0501
+#  endif
+#  if (_WIN32_WINNT < 0x0501) || (WINVER < 0x0501)
+#    error VS2008 does not support Windows build targets prior to WinXP
+#  endif
+#endif
+
 /* ---------------------------------------------------------------- */
 /*                         IPV6 COMPATIBILITY                       */
 /* ---------------------------------------------------------------- */