Added helper file for mingw binaries

hsbt · mrkn · commit 071b7c0b84c6 · 2017-07-12T19:20:19.000+09:00
diff --git a/lib/bigdecimal.rb b/lib/bigdecimal.rb
@@ -0,0 +1,5 @@
+begin
+  require "#{RUBY_VERSION[/\d+\.\d+/]}/bigdecimal.so"
+rescue LoadError
+  require 'bigdecimal.so'
+end
