Adds conditional byteswapping intrinsics

These intrinsics are synthesized, so maybe they should be in another
file. But since they are just a single line of code each, based on the
bswap intrinsics and aren't really intended for public consumption (they should be exposed as a
single function / trait) I thought they would fit here.
Implement `map_mut` on the Option type

Closes #7394
Classify newtype structs S(T) as immediates if T is an immediate
Fix dereference of temporary immediate newtype structs
Compare values in TreeMap's 'lt' function

Closes #5194
Small documentation changes

I'm leaving the Sized kind undocumented since it isn't fully implemented
yet.
GC static_size_of_enum, which was unused
Fixed documentation for finalize->drop change
Removing the rename warning

Now that the finalize->drop rename has happened, this hopefully
shouldn't end up changing again.
Fix make_mono_id to take into account self types. Closes #7536.
Make privacy checking on default methods for cross crate structs not fail. Closes #7481.

It is unclear to me that the way method call privacy checking is done
makes any sense, though. It is only performed if the type is a
struct...
Make the error messages that result from referencing
nonexistent traits consistent, and add a test.
Address @catamorphism's error message grammar nit.
rustc: improve -Z trans-stats to report per-fn LLVM instruction counts and translation timing
Added functionality to Base64 package

The Base64 package previously had extremely basic functionality. It only
suported the standard encoding character set, didn't support line breaks
and always padded output. This commit makes it significantly more
powerful.

The FromBase64 impl now supports all of the standard variants of Base64.
It ignores newlines,interprets '-' and '_' as well as '+' and '/' and
doesn't require padding. It isn't incredibly pedantic and will
successfully parse strings that are not strictly valid, but I don't
think the extra complexity required to make it accept _only_ valid
strings is worth it.

The ToBase64 trait has been modified such that to_base64 now takes a
base64::Config struct which contains the output format configuration.
This currently includes the selection of character set (standard or
url safe), whether or not to pad and an optional line break width. The
package comes with three static Config structs for the RFC 4648
standard, RFC 4648 url safe and RFC 2045 MIME formats.

The other option for configuring ToBase64 output would be to have one
method with the configuration flags passed and other traits with default
impls for the common cases, but I think that's a little messier.
Base64 API changes

There's now an enum to pick the character set instead of a url_safe
bool.

from_base64 now returns a Result<~[u8], ~str> and returns an Err instead
of killing the task when it is called on invalid input.

Fixed documentation examples.
Upper-cased exported statics
Add x64 windows to platform.mk and mingw64 header fixes.
Use #[allow(warnings)] in rusti instead of explicitly listing warnings
auto merge of #7543 : sanxiyn/rust/newtype-immediates, r=catamorphism

Fix #6612. Rebase of #6725. Fixed an additional bug and added a test.