[ruby/yaml] Expose YAML::VERSION

https://github.com/ruby/yaml/commit/8776bc2634

lib/yaml.rb

@@ -66,4 +66,5 @@ YAML = Psych # :nodoc:
 #
 # Syck can also be found on github: https://github.com/ruby/syck
 module YAML
+  VERSION = "0.2.1"
 end

lib/yaml/yaml.gemspec

@@ -1,6 +1,13 @@
+name = File.basename(__FILE__, ".gemspec")
+version = ["lib", Array.new(name.count("-")+1, "..").join("/")].find do |dir|
+  break File.foreach(File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")) do |line|
+    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+  end rescue nil
+end
+
 Gem::Specification.new do |spec|
-  spec.name          = "yaml"
-  spec.version       = "0.2.1"
+  spec.name          = name
+  spec.version       = version
   spec.authors       = ["Aaron Patterson", "SHIBATA Hiroshi"]
   spec.email         = ["aaron@tenderlovemaking.com", "hsbt@ruby-lang.org"]