merge revision(s) 51808: [Backport #11794]
* common.mk (update-gems): use BASERUBY instead of RUNRUBY.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@53006 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) 51808: [Backport #11794]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@53006 b2dd03c8-39d4-4d8f-98ff-823fe69b080e