envutil.rb: ensure errors

* test/ruby/envutil.rb (assert_separately): dump error and
  assertions by END to ensure outputs even if failed to catch the
  raised exception.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44123 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
test_exception.rb: ignore SystemStackError

* test/ruby/test_exception.rb (test_machine_stackoverflow): ignore
  propagated SystemStackError, which has not bee rescued in the
  child process by unknown reason.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44124 b2dd03c8-39d4-4d8f-98ff-823fe69b080e