Use std::fmt::radix instead of to_str_radix.

Signed-off-by: OGINO Masanori <masanori.ogino@gmail.com>
Mistake in AtomicBool spinlock example

The current example of a spinlock was not correct. The lock is actually acquired
when old == result. So we only need to deschedule when this is not the case.
Remove deprecated std::unstable module.

Signed-off-by: OGINO Masanori <masanori.ogino@gmail.com>
std: Add some implementation of common traits

- semver::Version is now Eq, Ord, and Hash
- Path is now PartialOrd and Ord
Document event_loop_factory usage

Add a couple of lines mentioning event_loop_factory - no clear error message is
given if you attempt to perform I/O in tasks created in this fashion.
More robust install.sh: do runnability test in fresh subdirectory.

Fix #15558.
auto merge of #15564 : alexcrichton/rust/moar-hash, r=huonw

- semver::Version is now Eq, Ord, and Hash
- Path is now PartialOrd and Ord
auto merge of #15570 : omasanori/rust/radix, r=alexcrichton
auto merge of #15574 : omasanori/rust/hidden, r=huonw
auto merge of #15575 : mvdnes/rust/spinlock_error, r=alexcrichton

The current example of a spinlock was not correct. The lock is actually acquired
when `old == result`. So we only need to deschedule when this is not the case.
auto merge of #15576 : mrmonday/rust/patch-1, r=alexcrichton

Add a couple of lines mentioning event_loop_factory - no clear error message is given if you attempt to perform I/O in tasks created in this fashion. I spent a many hours debugging this yesterday which would have been avoided if it were documented.
auto merge of #15580 : pnkfelix/rust/fsk-fix-15558, r=alexcrichton

Fix #15558.