merge revision(s) 39775: [Backport #8080]
* thread.c: disabled _FORTIFY_SOURCE for avoid to hit glibc bug. [Bug #8080] [ruby-core:53349] * test/ruby/test_io.rb (TestIO#test_io_select_with_many_files): test for the above.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@39840 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) 39775: [Backport #8080]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@39840 b2dd03c8-39d4-4d8f-98ff-823fe69b080e