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`.
mk: Fix _RUST_STAGEX variables under cross compile. Fix incoming
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?
auto merge of #6985 : Aatch/rust/fixed-vec-6977, r=thestinger

This fixes #6977. Negative counts don't make sense anyway.
Rename '#[inline(always)]' to '#[inline(force)]' and make 'always' emit a warning
Remove #[inline(always)] warnings from libstd
Remove #[inline(always)] warnings from libextra
Remove #[inline(always)] warnings from librustc
Remove #[inline(always)] warnings from libsyntax