two closures in the same function body can end up having
the same mangled name. This small patch uses gensym to
uniquely name each closure body so there won't be conflicts.

When a vec/str bounds check fails, include the bad index and the length of the str/vec in the fail message.

The stage0 compiler is not working on an x86_64 debian wheezy instance and it
looks like maye pthread_create is failing

Currently, the new version is ptr::p2::addr_of and the old one is
ptr::addr_of. This is kind of cheesy, but I need a snapshot before I
can ditch the old version, since the pipe compiler generates calls to
addr_of.

core is converted over to use the new version, std is not.