* configure.in: use quadrigraph to put '[' or ']'. [Bug #8192]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40027 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* configure.in: use 'test' instead quadrigraph.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40028 b2dd03c8-39d4-4d8f-98ff-823fe69b080e