configure.in: fix for old shells
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39741 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
configure.in: fix for old shells
available on old shells.
[Bug #7959] [Bug #8071]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39741 b2dd03c8-39d4-4d8f-98ff-823fe69b080e