Add mrbgem version field to lock file

lib/mruby/build.rb

@@ -43,7 +43,7 @@ module MRuby
     include Rake::DSL
     include LoadGems
     attr_accessor :name, :bins, :exts, :file_separator, :build_dir, :gem_clone_dir
-    attr_reader :libmruby_objs, :gems, :toolchains
+    attr_reader :libmruby_objs, :gems, :toolchains, :gem_dir_to_repo_url
     attr_writer :enable_bintest, :enable_test
 
     alias libmruby libmruby_objs
@@ -90,6 +90,7 @@ module MRuby
         @enable_test = false
         @enable_lock = true
         @toolchains = []
+        @gem_dir_to_repo_url = {}
 
         MRuby.targets[@name] = self
       end

lib/mruby/build/load_gems.rb

@@ -113,6 +113,7 @@ module MRuby
         end
 
         if lock_enabled?
+          @gem_dir_to_repo_url[gemdir] = url unless params[:path]
           locks[url] = {
             'url' => url,
             'branch' => git.current_branch(gemdir),

lib/mruby/gem.rb

@@ -91,6 +91,9 @@ module MRuby
         build.libmruby_objs << @objs
 
         instance_eval(&@build_config_initializer) if @build_config_initializer
+
+        repo_url = build.gem_dir_to_repo_url[dir]
+        build.locks[repo_url]['version'] = version if repo_url
       end
 
       def setup_compilers