[ruby/fiddle] Remove needless rescue

GitHub: fix GH-15

Reported by Eneroth3. Thanks!!!

https://github.com/ruby/fiddle/commit/f3d70b81ec

ext/fiddle/lib/fiddle/import.rb

@@ -83,11 +83,7 @@ module Fiddle
         when Importer
           lib.handlers
         else
-          begin
-            Fiddle.dlopen(lib)
-          rescue DLError
-            raise(DLError, "can't load #{lib}")
-          end
+          Fiddle.dlopen(lib)
         end
       }.flatten()
       @handler = CompositeHandler.new(handles)