Add outdate-bundled-gems target [ci skip]

common.mk

@@ -1400,6 +1400,17 @@ extract-gems$(gnumake:yes=-sequential): PHONY
 	    -e 'end' \
 	    gems/bundled_gems
 
+extract-gems: outdate-bundled-gems
+outdate-bundled-gems: PHONY
+	$(Q) $(BASERUBY) -C "$(srcdir)" \
+	-rfileutils \
+	-e 'Dir.glob(".bundle/gems/*/") {|g|' \
+	-e   'FileUtils::Verbose.rm_rf(g) unless File.exist?("gems/#{File.basename(g)}.gem")' \
+	-e '}' \
+	-e 'Dir.glob(".bundle/specifications/*.gemspec") {|g|' \
+	-e   'FileUtils::Verbose.rm_f(g) unless File.exist?("gems/#{File.basename(g, ".gemspec")}.gem")' \
+	-e '}'
+
 update-bundled_gems: PHONY
 	$(Q) $(RUNRUBY) -rrubygems \
 	     $(tooldir)/update-bundled_gems.rb \