* test/dl/test_base.rb: {libc, libm} detection now handle GNU/Hurd
  correctly. Patch by Gabriele Giacone (1o5g4r8o@gmail.com).
* test/fiddle/helper.rb: ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43077 b2dd03c8-39d4-4d8f-98ff-823fe69b080e