configure.in: fix lgamma_r condition
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54503 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
configure.in: fix lgamma_r condition
lgamma_r(-0.0). [Bug #12249]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54503 b2dd03c8-39d4-4d8f-98ff-823fe69b080e