Add #[deriving(Hash)] to Result.
mk/tests.mk: Fix a typo causing make to give compiletest the wrong rt build dir (target instead of host).
Remove rule that is confusing

The original text stated that one should only return a unique or managed pointer if you were given one in the first place. This makes it sound as if the function *should* return a unique pointer if it were given a unique pointer. The rest of the section goes on to describe why this is bad, and the example of bad code does exactly what the rule just said to do.

I reworded the original rule into a reference to the more concise rule mentioned at the bottom of the section, which helps add emphasis (a la 'it bears repeating').
auto merge of #13580 : DiamondLovesYou/rust/std-result-hash, r=alexcrichton

Title says it all.
auto merge of #13581 : DiamondLovesYou/rust/tests-mk-typo, r=alexcrichton

I spotted this while working on https://github.com/mozilla/rust/pull/13450.
auto merge of #13585 : brandonw/rust/patch-1, r=cmr

The original text stated that one should only return a unique or managed pointer if you were given one in the first place. This makes it sound as if the function *should* return a unique pointer if it were given a unique pointer. The rest of the section goes on to describe why this is bad, and the example of bad code does exactly what the rule just said to do.

I reworded the original rule into a reference to the more concise rule mentioned at the bottom of the section, which helps add emphasis (a la 'it bears repeating').