rust / build: make install should use explicit permissions when creating directories

Closes #10046
extra: Add getter methods to extra::rational::Ratio

After merging 0ada7c7, user code have not been able to access to `Ratio`'s numerator and denominator fields.
In some algorithms, it is needed to get an rational number's numerator or denominator, but keeping these fields private is necessary for guaranteeing that `Ratio` numbers are irreducible.
So, I added the getter methods `numer()` and `denom()`.

As a bonus, this commit adds utility methods relating to the ratio-integer conversion.
libextra: Make arc clone inline
libextra: Make arc::get and arc::new inline too.

Should be a 2x improvement in a Servo test case.
Fix a bug with the scheduler and destructor order

The PausibleIdleCallback must have some handle into the event loop, and because
struct destructors are run in order of top-to-bottom in order of fields, this
meant that the event loop was getting destroyed before the idle callback was
getting destroyed.

I can't confirm that this fixes a problem in how we use libuv, but it does
semantically fix a problem for usage with other event loops.
Remove the 'callback_ms' function from EventLoop

This is a peculiar function to require event loops to implement, and it's only
used in one spot during tests right now. Instead, a possibly more robust apis
for timers should be used rather than requiring all event loops to implement a
curious-looking function.
auto merge of #10055 : pcwalton/rust/arc-clone-inline, r=alexcrichton

r? @thestinger
stop trying to outsmart LLVM inline heuristics

Closes #10045
auto merge of #10059 : thestinger/rust/glue, r=pcwalton

Closes #10045
remove some dead trans code
libsyntax/librustc: Allow mut qualifier in patterns.
libsyntax: Get rid of some logic for some obsolete syntax.
Test for mut in ident patterns.
librustc: Don't emit unused mut lint twice.
libsyntax: Get rid of obsolete obsolete warning.
auto merge of #10061 : thestinger/rust/rustc, r=alexcrichton
Implement a basic event loop built on LittleLock

It's not guaranteed that there will always be an event loop to run, and this
implementation will serve as an incredibly basic one which does not provide any
I/O, but allows the scheduler to still run.

cc #9128
auto merge of #10054 : alexcrichton/rust/basic-event-loop, r=brson

This is more progress towards #9128 and all its related tree of issues. This implements a new `BasicLoop` on top of pthreads synchronization primitives (wrapped in `LittleLock`). This also removes the wonky `callback_ms` function from the interface of the event loop.

After #9901 is taking forever to land, I'm going to try to do all this runtime work in much smaller chunks than before. Right now this will not work unless #9901 lands first, but I'm close to landing it (hopefully), and I wanted to go ahead and get this reviewed before throwing it at bors later on down the road.

This "pausible idle callback" is also a bit of a weird idea, but it wasn't as difficult to implement as callback_ms so I'm more semi-ok with it.
Implement Clone trait for mutable unsafe pointers
Allow taking address of bottom