Do not create core file if it is intentional abort

Two tests abort intentionally and they create core files if
possible. In these case, we don't need to see core files
so disable by `"Process.setrlimit(Process::RLIMIT_CORE, 0)` for
those cases.

Author: ko1

test/-ext-/bug_reporter/test_bug_reporter.rb

@@ -19,9 +19,10 @@ def test_bug_reporter_add
     ]
     tmpdir = Dir.mktmpdir
 
+    no_core = "Process.setrlimit(Process::RLIMIT_CORE, 0); " if defined?(Process.setrlimit) && defined?(Process::RLIMIT_CORE)
     args = ["--disable-gems", "-r-test-/bug_reporter",
             "-C", tmpdir]
-    stdin = "register_sample_bug_reporter(12345); Process.kill :SEGV, $$"
+    stdin = "#{no_core}register_sample_bug_reporter(12345); Process.kill :SEGV, $$"
     assert_in_out_err(args, stdin, [], expected_stderr, encoding: "ASCII-8BIT")
   ensure
     FileUtils.rm_rf(tmpdir) if tmpdir

test/ruby/test_signal.rb

@@ -291,7 +291,8 @@ def test_ignored_interrupt
 
     if trap = Signal.list['TRAP']
       bug9820 = '[ruby-dev:48592] [Bug #9820]'
-      status = assert_in_out_err(['-e', 'Process.kill(:TRAP, $$)'])
+      no_core = "Process.setrlimit(Process::RLIMIT_CORE, 0); " if defined?(Process.setrlimit) && defined?(Process::RLIMIT_CORE)
+      status = assert_in_out_err(['-e', "#{no_core}Process.kill(:TRAP, $$)"])
       assert_predicate(status, :signaled?, bug9820)
       assert_equal(trap, status.termsig, bug9820)
     end