test/ruby/test_process.rb: ensure exit! on fork failure

* test/ruby/test_process.rb (test_deadlock_by_signal_at_forking):
  ensure exit! on fork failure

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48104 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
test/ruby/test_process.rb: use io/wait instead of timeout

Occasionally I get timeout errors during this test on an
overloaded system, so we may need to increase timeouts anyways.
For now, avoid the overhead of thread creation for every read we
do.

* test/ruby/test_process.rb (test_deadlock_by_signal_at_forking):
  use IO#wait_readable instead of timeout

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48105 b2dd03c8-39d4-4d8f-98ff-823fe69b080e