common.mk: fix command error

* common.mk (capi): flags cannot be separated by escaped newlines.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44625 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
test_rinda.rb: timeout all thread

* test/rinda/test_rinda.rb (test_do_reply): stop all threads and
  show backtraces.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44626 b2dd03c8-39d4-4d8f-98ff-823fe69b080e