testsuite: Add test cases, some xfailed

Closes #5060
Closes #4446
Closes #5192
mk: add mechanisms for triggering clean-llvm builds from commits
std: adjust run.rs test for android
ctags: add macros
librustc: don't skip ahead when computing register types of SSEFloatVectors

Also fixes an unrelated typo (found by comparing to the original code
of the clay project) and some cleanup.

Fixes #7415.
Optimize str::each_split_within when it is called with large limits
auto merge of #7441 : catamorphism/rust/testcases_2013-06-27, r=catamorphism
Add missing argument to a debug! call in trans_arg_expr
Avoid extra casts for "self" arguments

"self" is always passed as an opaque box, so there's no point in using
the concrete self type when translating the argument. All it does it
causing the value to be casted back to an opaque box right away.
auto merge of #7442 : graydon/rust/clean-llvm-trigger, r=brson

This makes it possible for us to trigger the llvm-clean make-target by checking in a change that touches rustllvm/llvm-auto-clean-stamp. Most developers don't need to see or know about this, but when you push a change that "needs an LLVM rebuild", even if not otherwise obvious, this should give a mechanism to do it.
Great renaming: propagate throughout the rest of the codebase
Fix merge fallout
Warning cleanup
Removing a lot of usage of '&const'
Remove mutability from unique boxes in the AST
Fix handling of temp cleanups for the "self" argument

The code that tried to revoke the cleanup for the self argument tried
to use "llself" to do so, but the cleanup might actually be registered
with a different ValueRef due to e.g. casting. Currently, this is
worked around by early revocation of the cleanup for self in
trans_self_arg.

To handle this correctly, we have to put the ValueRef for the cleanup
into the MethodData, so trans_call_inner can use it to revoke the
cleanup when it's actually supposed to.
Avoid double indirection for the "self" arg in methods

Currently we pass all "self" arguments by reference, for the pointer
variants this means that we end up with double indirection which causes
a unnecessary performance hit.

The fix itself is pretty straight-forward and just means that "self"
needs to be handled like any other argument, except for by-value "self"
which still needs to be passed by reference. This is because
non-pointer types can't just be stuffed into the environment slot which
is used to pass "self".

What made things tricky is that there was also a bug in the typechecker
where the method map entries are created. For type impls, that stored
the base type instead of the actual self-type in the method map, e.g.
Foo instead of &Foo for &self. That worked with pass-by-reference, but
fails with pass-by-value which needs the real type.

Code that makes use of methods seems to be about 10% faster with this
change. Also, build times are reduced by about 4%.

Fixes #4355, #4402, #5280, #4406 and #7285
auto merge of #7342 : alexcrichton/rust/assort-cleanup, r=cmr

This removes usage of `&const` throughout the standard libraries/compiler, and it removes some extraneous fields in the AST now that unique boxes always inherit their mutability.
auto merge of #7449 : yichoi/rust/std_test, r=cmr

adjust run.rs test for android to pass check std
fix code block syntax in two docstrings