add checking script

scripts/check_extract.rb

+#!/usr/bin/env ruby
+require_relative './common'
+
+watermark = WATERMARK
+
+METHODS.each do |method|
+  WASM_BINARIES.each do |id, file|
+    dir = Pathname(OUTPUT_DIRS[id])
+    a = dir + Pathname(file).basename.sub(".wasm", "-#{method[:abbr]}-#{watermark}.wasm")
+
+    OPT_PASSES.each do |pass|
+      b = a.sub(".wasm", "-#{pass}.wasm")
+      puts "#{a.basename} - #{b.basename}: #{method[:name]}, #{pass}, #{FileUtils.cmp(a, b)}"
+    end
+  end
+end