configure.in: fix for BSD make
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@35589 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
configure.in: fix for BSD make
only command, since BSD make does not work with it.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@35589 b2dd03c8-39d4-4d8f-98ff-823fe69b080e