Fix unicode errors on Windows in path_is_dir, path_exists, getcwd and rust_localtime.

This make these functions use wchar_t version of APIs, instead of char version.
auto merge of #9812 : HNO3/rust/windows-utf8, r=alexcrichton

This fixes #9418 and #9618, and potential problems related to directory walking.
fix typo
Don't allocate a string when calling println

Instead use format_args! to pass around a struct to pass along into std::fmt
auto merge of #9976 : thestinger/rust/typo, r=thestinger
expose new floating point intrinsics

copysign, ring, nearbyint, round
auto merge of #9979 : alexcrichton/rust/print-no-alloc, r=huonw

Instead use format_args! to pass around a struct to pass along into std::fmt
Add a feature flag for ASM
auto merge of #9991 : LeoTestard/rust/asm-feature-gate, r=huonw

Fixes #9882
Note that the actual checking code is inside a if false in order to compile libstd properly.
libstd uses asm! in rt. If we put ```#[feature(asm)]``` in libstd, it fails to build at stage0 beacause the
asm feature is not known yet by the snapshot compiler.
We must wait that this PR arrives into the snapshot in order to actually activate the checking code.
auto merge of #9986 : thestinger/rust/float, r=cmr

copysign, ring, nearbyint, round
rustpkg: Search for crates in the current directory

As per #8520, find crates in the current working directory even
if it's not a workspace.

Closes #8520
auto merge of #9736 : catamorphism/rust/rustpkg-issue-8520, r=cmr

r? @cmr As per #8520, find crates in the current working directory even
if it's not a workspace.

Closes #8520