Makefile.sub: fix nextafter
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45992 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Makefile.sub: fix nextafter
nextafter() as well as other mathematic functions. finite() and
isnan() used in missing/nextafter.c are not by older runtimes.
[Feature #9834]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45992 b2dd03c8-39d4-4d8f-98ff-823fe69b080e