Provide pathname.so with embedded Pathname

pathname.c

@@ -1591,6 +1591,8 @@ Init_pathname(void)
     rb_define_method(rb_cPathname, "delete", path_unlink, 0);
     rb_undef_method(rb_cPathname, "=~");
     rb_define_global_function("Pathname", path_f_pathname, 1);
+
+    rb_provide("pathname.so");
 }
 
 void

spec/ruby/core/kernel/require_spec.rb

@@ -19,6 +19,7 @@ describe "Kernel#require" do
   provided = %w[complex enumerator fiber rational thread ruby2_keywords]
   ruby_version_is "3.5" do
     provided << "set"
+    provided << "pathname"
   end
 
   it "#{provided.join(', ')} are already required" do
@@ -31,6 +32,10 @@ describe "Kernel#require" do
 
     features.sort.should == provided.sort
 
+    ruby_version_is "3.5" do
+      provided.map! { |f| f == "pathname" ? "pathname.so" : f }
+    end
+
     code = provided.map { |f| "puts require #{f.inspect}\n" }.join
     required = ruby_exe(code, options: '--disable-gems')
     required.should == "false\n" * provided.size