fail!() used to require owned strings but can handle static strings
now. Also, it can pass its arguments to fmt!() on its own, no need for
the caller to call fmt!() itself.
This also reverts some changes to TLS that were leaking memory.
Conflicts:
src/libcore/rt/uv/net.rs
src/libcore/task/local_data_priv.rs
src/libcore/unstable/lang.rs
A task without an unwinder will abort the process on failure.
I'm using this in the runtime tests to guarantee that a call to
`assert!` actually triggers some kind of failure (an abort)
instead of silently doing nothing. This is essentially in lieu
of a working linked failure implementation.
Things like the GC heap and unwinding are desirable everywhere the language
might be used, not just in tasks. All Rust code should have access to
LocalServices.
