[ruby/rubygems] Skip failing tests

ruby/rubygems@ee68fd8d20

Author: hsbt

test/rubygems/test_gem_ext_builder.rb

@@ -202,7 +202,8 @@ def test_build_extensions_install_ext_only
   end
 
   def test_build_multiple_extensions
-    pend "terminates on mswin" if vc_windows? && ruby_repo?
+    pend if RUBY_ENGINE == "truffleruby"
+    pend "terminates on ruby/ruby" if ruby_repo?
 
     extension_in_lib do
       @spec.extensions << "ext/Rakefile"