Moved copy_reg stub module to lib-old/.

Stub modules will be easier to track (and remove) if they are all kept
in lib-old/, instead of sprinkling them throughout the library.

diff --git a/Lib/copy_reg.py b/Lib/lib-old/copy_reg.py
similarity index 100%
rename from Lib/copy_reg.py
rename to Lib/lib-old/copy_reg.py