Remove chplcopygc.[ch] from the runtime

[Reviewed by David]

These files were from an early copying garbage collection framework.
Support for this was pulled from the compiler in r15107.

Removed them from the build as well.



git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@23614 3a8e244f-b0f2-452b-bcba-4c88e055c3ca