Don't fail if there is no makefile, simply don't do anything.

Author: ioquatix

lib/rubygems/ext/builder.rb

@@ -20,7 +20,8 @@ def self.class_name
 
   def self.make(dest_path, results, make_dir = Dir.pwd, sitedir = nil, targets = ["clean", "", "install"])
     unless File.exist? File.join(make_dir, "Makefile")
-      raise Gem::InstallError, "Makefile not found"
+      # No makefile exists, nothing to do.
+      return
     end
 
     # try to find make program from Ruby configure arguments first