add jemalloc to the runtime
integrate jemalloc into the build
Windows fixes
mk: Bulid rustrt with -pthread instead of -lpthread
libc: omit memcpy, memmove and memset

LLVM provides these functions as intrinsics, and will generate calls to
libc when appropriate. They are exposed in the `ptr` module as
`copy_nonoverlapping_memory`, `copy_memory` and `set_memory`.
Added iter::FromIter
Added IteratorUtil::collect
Removed IteratorUtil::to_vec and iter::to_vec
Fixups
add test cases for fold traversing macros
implement fold traversing macros
auto merge of #6980 : Kimundi/rust/iterator-collect3, r=thestinger
auto merge of #6981 : jbclements/rust/fold-traverses-macros, r=catamorphism

Fixes bug #2888 . Includes test cases

r? @catamorphism
Provide an actual error when expanding macros to foreign items
auto merge of #6982 : Aatch/rust/better-foreign-error, r=pcwalton

I encountered this. A straight fail is not useful and most people aren't going to happily spelunk in `parser.rs`
mk: Fix _RUST_STAGEX variables under cross compile. Fix incoming
Disallow negative counts in repeat expressions
auto merge of #6984 : brson/rust/rtcross, r=brson
auto merge of #6895 : cmr/rust/jemalloc, r=brson
auto merge of #6979 : thestinger/rust/libc, r=brson

LLVM provides these functions as intrinsics, and will generate calls to
libc when appropriate. They are exposed in the `ptr` module as
`copy_nonoverlapping_memory`, `copy_memory` and `set_memory`.

@graydon: r?