Experimental fix for ffi_closure_free causes dumping core/SEGV

http://u64.rubyci.org/~chkbuild/ruby-trunk/log/20130411T041301Z.log.html.gz#test%2F-ext-

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40233 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/dl/test_base.rb

@@ -130,5 +130,10 @@ module DL
 
     def test_empty()
     end
+
+    def teardown
+      if /linux/ =~ RUBY_PLATFORM
+        GC.start
+    end
   end
 end

test/fiddle/helper.rb

@@ -109,5 +109,10 @@ module Fiddle
       @libc = Fiddle.dlopen(LIBC_SO)
       @libm = Fiddle.dlopen(LIBM_SO)
     end
+
+    def teardown
+      if /linux/ =~ RUBY_PLATFORM
+        GC.start
+    end
   end
 end