test/ruby/test_signal.rb (test_sigchld_ignore): increase timeout

I suspect CI test machine was overloaded at the time,
or swapping at the time due to parallel build with mjit.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63962 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_signal.rb

@@ -350,7 +350,7 @@ class TestSignal < Test::Unit::TestCase
       zombies = pids.dup
       assert_nil r.read(1), 'children dead'
 
-      Timeout.timeout(3) do
+      Timeout.timeout(10) do
         zombies.delete_if do |pid|
           begin
             Process.kill(0, pid)