call GC.start before fork-related tests to decrease GC cost on fork children

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41911 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_notimp.rb

@@ -21,6 +21,7 @@ class TestNotImplement < Test::Unit::TestCase
   end
 
   def test_call_fork
+    GC.start
     pid = nil
     begin
       Timeout.timeout(5) {

test/ruby/test_rand.rb

@@ -437,6 +437,7 @@ END
   end
 
   def test_rand_reseed_on_fork
+    GC.start
     bug5661 = '[ruby-core:41209]'
 
     assert_fork_status(1, bug5661) {Random.rand(4)}