win32/resolv.rb: call rb_w32_osid

* ext/win32/lib/win32/resolv.rb: call rb_w32_osid instead of
  direct GetVersionExA API.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61895 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/win32/lib/win32/resolv.rb

@@ -42,19 +42,19 @@ begin
 rescue LoadError
 end
 
-nt = Module.new do
-  break true if [nil].pack("p").size > 4
-  extend Importer
-  dlload "kernel32.dll"
-  getv = extern "int GetVersionExA(void *)", :stdcall
-  info = [ 148, 0, 0, 0, 0 ].pack('V5') + "\0" * 128
-  getv.call(info)
-  break info.unpack('V5')[4] == 2  # VER_PLATFORM_WIN32_NT
+if [nil].pack("p").size <= 4 # 32bit env
+  begin
+    f = Fiddle
+    osid = f::Handle.new["rb_w32_osid"]
+  rescue f::DLError # not ix86, cannot be Windows 9x
+  else
+    if f::Function.new(osid, [], f::TYPE_INT).call < 2  # VER_PLATFORM_WIN32_NT
+      require_relative 'resolv9x'
+      return
+    end
+  end
 end
-if not nt
-  require_relative 'resolv9x'
-  # return # does not work yet
-else
+
 module Win32
 #====================================================================
 # Windows NT
@@ -146,4 +146,3 @@ module Win32
     end
   end
 end
-end