fix the ptr::set_memory docstring
fix the docstring for copy_nonoverlapping_memory
auto merge of #7072 : thestinger/rust/ptr, r=catamorphism

I don't think this will even show up in the documentation right now.... but it should still be correct :).
librustc: Don't allow duplicate methods on a trait.
librustc: Don't allow duplicate methods on impls.
Add tests for duplicate methods on traits/impls.
libsyntax: Remove duplicate methods.
auto merge of #7064 : luqmana/rust/issue-7062, r=sanxiyn

Fixes #7062
Rewrite rusti