lgamma_r.c: fix at -0.0
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54496 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
lgamma_r.c: fix at -0.0
since msvcrt does not provide it.
[ruby-core:74823] [Bug #12249]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54496 b2dd03c8-39d4-4d8f-98ff-823fe69b080e