Only set sysconfdir on Windows

Author: andyundso

ext/tiny_tds/extconf.rb

@@ -115,7 +115,7 @@ def configure_defaults
 
     recipe.configure_options << "--with-openssl=#{openssl_recipe.path}"
     recipe.configure_options << "--with-libiconv-prefix=#{libiconv_recipe.path}"
-    recipe.configure_options << "--sysconfdir=#{MiniPortile.windows? ? "C:/Sites" : "/usr/local/etc"}"
+    recipe.configure_options << "--sysconfdir=C:/Sites" if MiniPortile.windows?
 
     recipe.gem_platform = gem_platform
     recipe.cook_and_activate