add build test for a builder waiting on another builder

build_tests/simple/builder_wait_for_builder.rb

@@ -0,0 +1,23 @@
+class MyObject < Rscons::Builder
+  def run(options)
+    if @builder
+      if File.exists?(@target)
+        true
+      else
+        false
+      end
+    else
+      @env.print_builder_run_message("#{name} #{@target}", nil)
+      @builder = @env.Object(@target, @sources, @vars)
+      wait_for(@builder)
+    end
+  end
+end
+
+build do
+  Environment.new do |env|
+    env.add_builder(MyObject)
+    env.MyObject("simple.o", "simple.c")
+    env.Program("simple.exe", "simple.o")
+  end
+end