include/ruby/ruby.h: comment about mswin RUBY_EXTERN [ci skip]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64965 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

include/ruby/ruby.h

@@ -28,7 +28,8 @@ extern "C" {
 
 #include "defines.h"
 
-/* For MinGW, we need __declspec(dllimport) for RUBY_EXTERN on MJIT. mswin's RUBY_EXTERN already has that. */
+/* For MinGW, we need __declspec(dllimport) for RUBY_EXTERN on MJIT.
+   mswin's RUBY_EXTERN already has that. See also: win32/Makefile.sub */ 
 #if defined(MJIT_HEADER) && defined(_WIN32) && defined(__GNUC__)
 # undef RUBY_EXTERN
 # define RUBY_EXTERN extern __declspec(dllimport)