gmake.mk: mflags without -jN
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57635 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
gmake.mk: mflags without -jN
without -jN option.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57635 b2dd03c8-39d4-4d8f-98ff-823fe69b080e