backout -r2827 and add correct fix

auto/configure

diff --git a/auto/configure b/auto/configure
index 9a72db4..5e9c262 100755
--- a/auto/configure
+++ b/auto/configure
@@ -31,6 +31,12 @@
 
     NGX_PLATFORM="$NGX_SYSTEM:$NGX_RELEASE:$NGX_MACHINE";
 
+    case "$NGX_SYSTEM" in
+        MINGW32_*)
+            NGX_PLATFORM=win32
+        ;;
+    esac
+
 else
     echo "building for $NGX_PLATFORM"
     NGX_SYSTEM=$NGX_PLATFORM

auto/os/conf

diff --git a/auto/os/conf b/auto/os/conf
index 9bd5ee3..f4d08cb 100644
--- a/auto/os/conf
+++ b/auto/os/conf
@@ -22,7 +22,7 @@
         . auto/os/darwin
     ;;
 
-    win32 | MINGW32_* )
+    win32)
         . auto/os/win32
     ;;