librustc: Implement `#[no_main]`, which omits the entry point entirely.

Useful for SDL and possibly Android too.
Additional check in treemap iterator test.
Remove redundant print.
Implemented TreeMap::{lower_bound_iter,upper_bound_iter}

(issue #4604)
std::rt: Use magic to make TLS work from annihilated boxes. #8302
auto merge of #8303 : brson/rust/tls-magic-wtf, r=brson
auto merge of #8227 : dim-an/rust/tree-iter, r=thestinger
auto merge of #8279 : pcwalton/rust/no-main, r=brson

Useful for SDL and possibly Android too.

r? @brson