* modify macro to detect 'MacOS X' based on [ruby-talk:77849]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@4293 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

process.c

@@ -72,7 +72,7 @@ static VALUE S_Tms;
 #define WSTOPSIG        WEXITSTATUS
 #endif
 
-#if defined(__APPLE__) && defined(__MACH__) && !defined(__MacOS_X__)
+#if defined(__APPLE__) && ( defined(__MACH__) || defined(__DARWIN__) ) && !defined(__MacOS_X__)
 #define __MacOS_X__ 1
 #endif