ruby.c: argv check
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37823 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
ruby.c: argv check
care of the case argc is 0, and check if argv has NULL.
[ruby-core:49889] [Bug #7423]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37823 b2dd03c8-39d4-4d8f-98ff-823fe69b080e