common.mk: simplify for ruby.imp
sort -u
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65983 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
common.mk: simplify for ruby.imp
of MJIT_FUNC_EXPORTED, regardless the prefix. duplicate symbols
will be removed by
sort -u.git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65983 b2dd03c8-39d4-4d8f-98ff-823fe69b080e