pass Builder object to build hooks instead of build_operation Hash

build_tests/simple/register_target_in_build_hook.rb

@@ -1,9 +1,9 @@
 build do
   Environment.new do |env|
     env.Program("simple.exe", Dir["*.c"])
-    env.add_build_hook do |build_op|
-      if build_op[:target].end_with?(".o")
-        env.Disassemble("#{build_op[:target]}.txt", build_op[:target])
+    env.add_build_hook do |builder|
+      if builder.target.end_with?(".o")
+        env.Disassemble("#{builder.target}.txt", builder.target)
       end
     end
   end