rustdoc: Remove a now invalid test
pipes: use finally to fix pipes::try_recv
avoid broken += operator, bogus use of const
auto merge of #6148 : erickt/rust/remove-drop, r=pcwalton

The drop block has been deprecated for quite some time. This patch series removes support for parsing it and all the related machinery that made drop work.

As a side feature of all this, I also added the ability to annote fields in structs. This allows comments to be properly associated with an individual field. However, I didn't update `rustdoc` to integrate these comment blocks into the documentation it generates.
wip---work on making rooting work properly
compiletest: stop ignoring all tests.
libstd: impl Clone for BigUint/BigInt and replace `copy` with `.clone()`
Add trait object field types to back/abi.rs, and use them

I've added trt_field_vtable, trt_field_box, and trt_field_tydesc, and
inserted them in place of the "magic numbers" used to access trait
object fields through GEPi().
libc bindings for glob.h

only tested on linux/x86_64, but i got the values for other platforms
from their system header files.

no bindings for win32, because win32 doesn't include glob.h.

also, glob() takes a callback for error handling, but i'm just making
this a *c_void for now, since i don't know how to represent c calling
back into rust (if that's even currently possible).
add a higher level glob() function to os

this could probably use expansion - it just uses all of the default
options, which is usually what we want, but not always. maybe add a
separate function that takes more options?
glob_t should be public on all platforms
libcore: add N(0,1) and Exp(1) distributions to core::rand.

Sample from the normal and exponential distributions using the Ziggurat
algorithm.
auto merge of #6161 : graydon/rust/glob-retry, r=graydon

This is a retry of pull #5832
mk: minor fix for test.mk to support mutiple target test
rustc: adjust total number of lang items
rustc: fix the fact that trans_lvalue rooted twice
core: add more debugging printouts to borrowing
auto merge of #6162 : graydon/rust/random-retry, r=graydon

Sample from the normal and exponential distributions using the Ziggurat
algorithm.
Take string slices
Use static strings