ext/rbconfig/sizeof: distclean

* ext/rbconfig/sizeof/extconf.rb: clean sizes.c at distclean.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46704 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
common.mk: empty by distclean

* common.mk (clean-runnable): remove files made by mkrunnable.

* common.mk (clean-extout): remove archir too.

* common.mk (clean-ext): remove timestamp directory

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46705 b2dd03c8-39d4-4d8f-98ff-823fe69b080e