where they are supported. modifing environ variable seems to
  segfault solaris 10. [ruby-core:7276] [ruby-dev:28270]

* ruby.c (set_arg0): if use setenv(3), environ space cannot be used
  for altering argv[0].


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@9868 b2dd03c8-39d4-4d8f-98ff-823fe69b080e