don't force windows versions if they are set in the environment

diff --git a/configure.ac b/configure.ac
index 41ba5a49b962685d2c4f458d8d7c6b6d11a3b411..fbb7b3c25bf4996c479c560b0258067393cca10d 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -245,9 +245,23 @@ AM_CONDITIONAL([STATIC_BSDCPIO], [ test "$static_bsdcpio" = yes ])
 # Set up defines needed before including any headers
 case $host in
   *mingw* | *cygwin* | *msys*  )
-  AC_DEFINE([_WIN32_WINNT], 0x0502, [Define to '0x0502' for Windows Server 2003 APIs.])
-  AC_DEFINE([WINVER], 0x0502, [Define to '0x0502' for Windows Server 2003 APIs.])
-  AC_DEFINE([NTDDI_VERSION], 0x05020000, [Define to '0x05020000' for Windows Server 2003 APIs.])
+  AC_PREPROC_IFELSE([AC_LANG_PROGRAM(
+    [[#ifdef _WIN32_WINNT
+     # error _WIN32_WINNT already defined
+     #endif
+    ]],[[;]])
+  ],[
+    AC_DEFINE([_WIN32_WINNT], 0x0502, [Define to '0x0502' for Windows Server 2003 APIs.])
+    AC_DEFINE([NTDDI_VERSION], 0x05020000, [Define to '0x05020000' for Windows Server 2003 APIs.])
+  ])
+  AC_PREPROC_IFELSE([AC_LANG_PROGRAM(
+    [[#ifdef WINVER
+     # error WINVER already defined
+     #endif
+    ]],[[;]])
+  ],[
+    AC_DEFINE([WINVER], 0x0502, [Define to '0x0502' for Windows Server 2003 APIs.])
+  ])
   ;;
 esac